From 55f3560df975f557c48aa6afc636808f31ecb87a Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:15 +0200 Subject: seqlock: Extend seqcount API with associated locks A sequence counter write side critical section must be protected by some form of locking to serialize writers. If the serialization primitive is not disabling preemption implicitly, preemption has to be explicitly disabled before entering the write side critical section. There is no built-in debugging mechanism to verify that the lock used for writer serialization is held and preemption is disabled. Some usage sites like dma-buf have explicit lockdep checks for the writer-side lock, but this covers only a small portion of the sequence counter usage in the kernel. Add new sequence counter types which allows to associate a lock to the sequence counter at initialization time. The seqcount API functions are extended to provide appropriate lockdep assertions depending on the seqcount/lock type. For sequence counters with associated locks that do not implicitly disable preemption, preemption protection is enforced in the sequence counter write side functions. This removes the need to explicitly add preempt_disable/enable() around the write side critical sections: the write_begin/end() functions for these new sequence counter types automatically do this. Introduce the following seqcount types with associated locks: seqcount_spinlock_t seqcount_raw_spinlock_t seqcount_rwlock_t seqcount_mutex_t seqcount_ww_mutex_t Extend the seqcount read and write functions to branch out to the specific seqcount_LOCKTYPE_t implementation at compile-time. This avoids kernel API explosion per each new seqcount_LOCKTYPE_t added. Add such compile-time type detection logic into a new, internal, seqlock header. Document the proper seqcount_LOCKTYPE_t usage, and rationale, at Documentation/locking/seqlock.rst. If lockdep is disabled, this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-10-a.darwish@linutronix.de --- include/linux/seqlock.h | 464 +++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 395 insertions(+), 69 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 54bc20496392..8c16a494c968 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -10,13 +10,17 @@ * * Copyrights: * - Based on x86_64 vsyscall gettimeofday: Keith Owens, Andrea Arcangeli + * - Sequence counters with associated locks, (C) 2020 Linutronix GmbH */ -#include -#include -#include #include #include +#include +#include +#include +#include +#include + #include /* @@ -48,6 +52,10 @@ * This mechanism can't be used if the protected data contains pointers, * as the writer can invalidate a pointer that a reader is following. * + * If the write serialization mechanism is one of the common kernel + * locking primitives, use a sequence counter with associated lock + * (seqcount_LOCKTYPE_t) instead. + * * If it's desired to automatically handle the sequence counter writer * serialization and non-preemptibility requirements, use a sequential * lock (seqlock_t) instead. @@ -108,9 +116,267 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s) */ #define SEQCNT_ZERO(name) { .sequence = 0, SEQCOUNT_DEP_MAP_INIT(name) } +/* + * Sequence counters with associated locks (seqcount_LOCKTYPE_t) + * + * A sequence counter which associates the lock used for writer + * serialization at initialization time. This enables lockdep to validate + * that the write side critical section is properly serialized. + * + * For associated locks which do not implicitly disable preemption, + * preemption protection is enforced in the write side function. + * + * Lockdep is never used in any for the raw write variants. + * + * See Documentation/locking/seqlock.rst + */ + +#ifdef CONFIG_LOCKDEP +#define __SEQ_LOCKDEP(expr) expr +#else +#define __SEQ_LOCKDEP(expr) +#endif + +#define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) { \ + .seqcount = SEQCNT_ZERO(seq_name.seqcount), \ + __SEQ_LOCKDEP(.lock = (assoc_lock)) \ +} + +#define seqcount_locktype_init(s, assoc_lock) \ +do { \ + seqcount_init(&(s)->seqcount); \ + __SEQ_LOCKDEP((s)->lock = (assoc_lock)); \ +} while (0) + +/** + * typedef seqcount_spinlock_t - sequence counter with spinlock associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated spinlock + * + * A plain sequence counter with external writer synchronization by a + * spinlock. The spinlock is associated to the sequence count in the + * static initializer or init function. This enables lockdep to validate + * that the write side critical section is properly serialized. + */ +typedef struct seqcount_spinlock { + seqcount_t seqcount; + __SEQ_LOCKDEP(spinlock_t *lock); +} seqcount_spinlock_t; + +/** + * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t + * @name: Name of the seqcount_spinlock_t instance + * @lock: Pointer to the associated spinlock + */ +#define SEQCNT_SPINLOCK_ZERO(name, lock) \ + SEQCOUNT_LOCKTYPE_ZERO(name, lock) + +/** + * seqcount_spinlock_init - runtime initializer for seqcount_spinlock_t + * @s: Pointer to the seqcount_spinlock_t instance + * @lock: Pointer to the associated spinlock + */ +#define seqcount_spinlock_init(s, lock) \ + seqcount_locktype_init(s, lock) + +/** + * typedef seqcount_raw_spinlock_t - sequence count with raw spinlock associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated raw spinlock + * + * A plain sequence counter with external writer synchronization by a + * raw spinlock. The raw spinlock is associated to the sequence count in + * the static initializer or init function. This enables lockdep to + * validate that the write side critical section is properly serialized. + */ +typedef struct seqcount_raw_spinlock { + seqcount_t seqcount; + __SEQ_LOCKDEP(raw_spinlock_t *lock); +} seqcount_raw_spinlock_t; + +/** + * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t + * @name: Name of the seqcount_raw_spinlock_t instance + * @lock: Pointer to the associated raw_spinlock + */ +#define SEQCNT_RAW_SPINLOCK_ZERO(name, lock) \ + SEQCOUNT_LOCKTYPE_ZERO(name, lock) + +/** + * seqcount_raw_spinlock_init - runtime initializer for seqcount_raw_spinlock_t + * @s: Pointer to the seqcount_raw_spinlock_t instance + * @lock: Pointer to the associated raw_spinlock + */ +#define seqcount_raw_spinlock_init(s, lock) \ + seqcount_locktype_init(s, lock) + +/** + * typedef seqcount_rwlock_t - sequence count with rwlock associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated rwlock + * + * A plain sequence counter with external writer synchronization by a + * rwlock. The rwlock is associated to the sequence count in the static + * initializer or init function. This enables lockdep to validate that + * the write side critical section is properly serialized. + */ +typedef struct seqcount_rwlock { + seqcount_t seqcount; + __SEQ_LOCKDEP(rwlock_t *lock); +} seqcount_rwlock_t; + +/** + * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t + * @name: Name of the seqcount_rwlock_t instance + * @lock: Pointer to the associated rwlock + */ +#define SEQCNT_RWLOCK_ZERO(name, lock) \ + SEQCOUNT_LOCKTYPE_ZERO(name, lock) + +/** + * seqcount_rwlock_init - runtime initializer for seqcount_rwlock_t + * @s: Pointer to the seqcount_rwlock_t instance + * @lock: Pointer to the associated rwlock + */ +#define seqcount_rwlock_init(s, lock) \ + seqcount_locktype_init(s, lock) + +/** + * typedef seqcount_mutex_t - sequence count with mutex associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated mutex + * + * A plain sequence counter with external writer synchronization by a + * mutex. The mutex is associated to the sequence counter in the static + * initializer or init function. This enables lockdep to validate that + * the write side critical section is properly serialized. + * + * The write side API functions write_seqcount_begin()/end() automatically + * disable and enable preemption when used with seqcount_mutex_t. + */ +typedef struct seqcount_mutex { + seqcount_t seqcount; + __SEQ_LOCKDEP(struct mutex *lock); +} seqcount_mutex_t; + +/** + * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t + * @name: Name of the seqcount_mutex_t instance + * @lock: Pointer to the associated mutex + */ +#define SEQCNT_MUTEX_ZERO(name, lock) \ + SEQCOUNT_LOCKTYPE_ZERO(name, lock) + +/** + * seqcount_mutex_init - runtime initializer for seqcount_mutex_t + * @s: Pointer to the seqcount_mutex_t instance + * @lock: Pointer to the associated mutex + */ +#define seqcount_mutex_init(s, lock) \ + seqcount_locktype_init(s, lock) + +/** + * typedef seqcount_ww_mutex_t - sequence count with ww_mutex associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated ww_mutex + * + * A plain sequence counter with external writer synchronization by a + * ww_mutex. The ww_mutex is associated to the sequence counter in the static + * initializer or init function. This enables lockdep to validate that + * the write side critical section is properly serialized. + * + * The write side API functions write_seqcount_begin()/end() automatically + * disable and enable preemption when used with seqcount_ww_mutex_t. + */ +typedef struct seqcount_ww_mutex { + seqcount_t seqcount; + __SEQ_LOCKDEP(struct ww_mutex *lock); +} seqcount_ww_mutex_t; + +/** + * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t + * @name: Name of the seqcount_ww_mutex_t instance + * @lock: Pointer to the associated ww_mutex + */ +#define SEQCNT_WW_MUTEX_ZERO(name, lock) \ + SEQCOUNT_LOCKTYPE_ZERO(name, lock) + +/** + * seqcount_ww_mutex_init - runtime initializer for seqcount_ww_mutex_t + * @s: Pointer to the seqcount_ww_mutex_t instance + * @lock: Pointer to the associated ww_mutex + */ +#define seqcount_ww_mutex_init(s, lock) \ + seqcount_locktype_init(s, lock) + +/* + * @preempt: Is the associated write serialization lock preemtpible? + */ +#define SEQCOUNT_LOCKTYPE(locktype, preempt, lockmember) \ +static inline seqcount_t * \ +__seqcount_##locktype##_ptr(seqcount_##locktype##_t *s) \ +{ \ + return &s->seqcount; \ +} \ + \ +static inline bool \ +__seqcount_##locktype##_preemptible(seqcount_##locktype##_t *s) \ +{ \ + return preempt; \ +} \ + \ +static inline void \ +__seqcount_##locktype##_assert(seqcount_##locktype##_t *s) \ +{ \ + __SEQ_LOCKDEP(lockdep_assert_held(lockmember)); \ +} + +/* + * Similar hooks, but for plain seqcount_t + */ + +static inline seqcount_t *__seqcount_ptr(seqcount_t *s) +{ + return s; +} + +static inline bool __seqcount_preemptible(seqcount_t *s) +{ + return false; +} + +static inline void __seqcount_assert(seqcount_t *s) +{ + lockdep_assert_preemption_disabled(); +} + +/* + * @s: Pointer to seqcount_locktype_t, generated hooks first parameter. + */ +SEQCOUNT_LOCKTYPE(raw_spinlock, false, s->lock) +SEQCOUNT_LOCKTYPE(spinlock, false, s->lock) +SEQCOUNT_LOCKTYPE(rwlock, false, s->lock) +SEQCOUNT_LOCKTYPE(mutex, true, s->lock) +SEQCOUNT_LOCKTYPE(ww_mutex, true, &s->lock->base) + +#define __seqprop_case(s, locktype, prop) \ + seqcount_##locktype##_t: __seqcount_##locktype##_##prop((void *)(s)) + +#define __seqprop(s, prop) _Generic(*(s), \ + seqcount_t: __seqcount_##prop((void *)(s)), \ + __seqprop_case((s), raw_spinlock, prop), \ + __seqprop_case((s), spinlock, prop), \ + __seqprop_case((s), rwlock, prop), \ + __seqprop_case((s), mutex, prop), \ + __seqprop_case((s), ww_mutex, prop)) + +#define __to_seqcount_t(s) __seqprop(s, ptr) +#define __associated_lock_exists_and_is_preemptible(s) __seqprop(s, preemptible) +#define __assert_write_section_is_protected(s) __seqprop(s, assert) + /** * __read_seqcount_begin() - begin a seqcount_t read section w/o barrier - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * __read_seqcount_begin is like read_seqcount_begin, but has no smp_rmb() * barrier. Callers should ensure that smp_rmb() or equivalent ordering is @@ -122,7 +388,10 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s) * * Return: count to be passed to read_seqcount_retry() */ -static inline unsigned __read_seqcount_begin(const seqcount_t *s) +#define __read_seqcount_begin(s) \ + __read_seqcount_t_begin(__to_seqcount_t(s)) + +static inline unsigned __read_seqcount_t_begin(const seqcount_t *s) { unsigned ret; @@ -138,32 +407,38 @@ repeat: /** * raw_read_seqcount_begin() - begin a seqcount_t read section w/o lockdep - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * Return: count to be passed to read_seqcount_retry() */ -static inline unsigned raw_read_seqcount_begin(const seqcount_t *s) +#define raw_read_seqcount_begin(s) \ + raw_read_seqcount_t_begin(__to_seqcount_t(s)) + +static inline unsigned raw_read_seqcount_t_begin(const seqcount_t *s) { - unsigned ret = __read_seqcount_begin(s); + unsigned ret = __read_seqcount_t_begin(s); smp_rmb(); return ret; } /** * read_seqcount_begin() - begin a seqcount_t read critical section - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * Return: count to be passed to read_seqcount_retry() */ -static inline unsigned read_seqcount_begin(const seqcount_t *s) +#define read_seqcount_begin(s) \ + read_seqcount_t_begin(__to_seqcount_t(s)) + +static inline unsigned read_seqcount_t_begin(const seqcount_t *s) { seqcount_lockdep_reader_access(s); - return raw_read_seqcount_begin(s); + return raw_read_seqcount_t_begin(s); } /** * raw_read_seqcount() - read the raw seqcount_t counter value - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * raw_read_seqcount opens a read critical section of the given * seqcount_t, without any lockdep checking, and without checking or @@ -172,7 +447,10 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s) * * Return: count to be passed to read_seqcount_retry() */ -static inline unsigned raw_read_seqcount(const seqcount_t *s) +#define raw_read_seqcount(s) \ + raw_read_seqcount_t(__to_seqcount_t(s)) + +static inline unsigned raw_read_seqcount_t(const seqcount_t *s) { unsigned ret = READ_ONCE(s->sequence); smp_rmb(); @@ -183,7 +461,7 @@ static inline unsigned raw_read_seqcount(const seqcount_t *s) /** * raw_seqcount_begin() - begin a seqcount_t read critical section w/o * lockdep and w/o counter stabilization - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * raw_seqcount_begin opens a read critical section of the given * seqcount_t. Unlike read_seqcount_begin(), this function will not wait @@ -197,18 +475,21 @@ static inline unsigned raw_read_seqcount(const seqcount_t *s) * * Return: count to be passed to read_seqcount_retry() */ -static inline unsigned raw_seqcount_begin(const seqcount_t *s) +#define raw_seqcount_begin(s) \ + raw_seqcount_t_begin(__to_seqcount_t(s)) + +static inline unsigned raw_seqcount_t_begin(const seqcount_t *s) { /* * If the counter is odd, let read_seqcount_retry() fail * by decrementing the counter. */ - return raw_read_seqcount(s) & ~1; + return raw_read_seqcount_t(s) & ~1; } /** * __read_seqcount_retry() - end a seqcount_t read section w/o barrier - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * @start: count, from read_seqcount_begin() * * __read_seqcount_retry is like read_seqcount_retry, but has no smp_rmb() @@ -221,7 +502,10 @@ static inline unsigned raw_seqcount_begin(const seqcount_t *s) * * Return: true if a read section retry is required, else false */ -static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) +#define __read_seqcount_retry(s, start) \ + __read_seqcount_t_retry(__to_seqcount_t(s), start) + +static inline int __read_seqcount_t_retry(const seqcount_t *s, unsigned start) { kcsan_atomic_next(0); return unlikely(READ_ONCE(s->sequence) != start); @@ -229,7 +513,7 @@ static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) /** * read_seqcount_retry() - end a seqcount_t read critical section - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * @start: count, from read_seqcount_begin() * * read_seqcount_retry closes the read critical section of given @@ -238,17 +522,28 @@ static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start) * * Return: true if a read section retry is required, else false */ -static inline int read_seqcount_retry(const seqcount_t *s, unsigned start) +#define read_seqcount_retry(s, start) \ + read_seqcount_t_retry(__to_seqcount_t(s), start) + +static inline int read_seqcount_t_retry(const seqcount_t *s, unsigned start) { smp_rmb(); - return __read_seqcount_retry(s, start); + return __read_seqcount_t_retry(s, start); } /** * raw_write_seqcount_begin() - start a seqcount_t write section w/o lockdep - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants */ -static inline void raw_write_seqcount_begin(seqcount_t *s) +#define raw_write_seqcount_begin(s) \ +do { \ + if (__associated_lock_exists_and_is_preemptible(s)) \ + preempt_disable(); \ + \ + raw_write_seqcount_t_begin(__to_seqcount_t(s)); \ +} while (0) + +static inline void raw_write_seqcount_t_begin(seqcount_t *s) { kcsan_nestable_atomic_begin(); s->sequence++; @@ -257,49 +552,50 @@ static inline void raw_write_seqcount_begin(seqcount_t *s) /** * raw_write_seqcount_end() - end a seqcount_t write section w/o lockdep - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants */ -static inline void raw_write_seqcount_end(seqcount_t *s) +#define raw_write_seqcount_end(s) \ +do { \ + raw_write_seqcount_t_end(__to_seqcount_t(s)); \ + \ + if (__associated_lock_exists_and_is_preemptible(s)) \ + preempt_enable(); \ +} while (0) + +static inline void raw_write_seqcount_t_end(seqcount_t *s) { smp_wmb(); s->sequence++; kcsan_nestable_atomic_end(); } -static inline void __write_seqcount_begin_nested(seqcount_t *s, int subclass) -{ - raw_write_seqcount_begin(s); - seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_); -} - /** * write_seqcount_begin_nested() - start a seqcount_t write section with * custom lockdep nesting level - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * @subclass: lockdep nesting level * * See Documentation/locking/lockdep-design.rst */ -static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass) -{ - lockdep_assert_preemption_disabled(); - __write_seqcount_begin_nested(s, subclass); -} - -/* - * A write_seqcount_begin() variant w/o lockdep non-preemptibility checks. - * - * Use for internal seqlock.h code where it's known that preemption is - * already disabled. For example, seqlock_t write side functions. - */ -static inline void __write_seqcount_begin(seqcount_t *s) +#define write_seqcount_begin_nested(s, subclass) \ +do { \ + __assert_write_section_is_protected(s); \ + \ + if (__associated_lock_exists_and_is_preemptible(s)) \ + preempt_disable(); \ + \ + write_seqcount_t_begin_nested(__to_seqcount_t(s), subclass); \ +} while (0) + +static inline void write_seqcount_t_begin_nested(seqcount_t *s, int subclass) { - __write_seqcount_begin_nested(s, 0); + raw_write_seqcount_t_begin(s); + seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_); } /** * write_seqcount_begin() - start a seqcount_t write side critical section - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * write_seqcount_begin opens a write side critical section of the given * seqcount_t. @@ -308,26 +604,44 @@ static inline void __write_seqcount_begin(seqcount_t *s) * non-preemptible. If readers can be invoked from hardirq or softirq * context, interrupts or bottom halves must be respectively disabled. */ -static inline void write_seqcount_begin(seqcount_t *s) +#define write_seqcount_begin(s) \ +do { \ + __assert_write_section_is_protected(s); \ + \ + if (__associated_lock_exists_and_is_preemptible(s)) \ + preempt_disable(); \ + \ + write_seqcount_t_begin(__to_seqcount_t(s)); \ +} while (0) + +static inline void write_seqcount_t_begin(seqcount_t *s) { - write_seqcount_begin_nested(s, 0); + write_seqcount_t_begin_nested(s, 0); } /** * write_seqcount_end() - end a seqcount_t write side critical section - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * The write section must've been opened with write_seqcount_begin(). */ -static inline void write_seqcount_end(seqcount_t *s) +#define write_seqcount_end(s) \ +do { \ + write_seqcount_t_end(__to_seqcount_t(s)); \ + \ + if (__associated_lock_exists_and_is_preemptible(s)) \ + preempt_enable(); \ +} while (0) + +static inline void write_seqcount_t_end(seqcount_t *s) { seqcount_release(&s->dep_map, _RET_IP_); - raw_write_seqcount_end(s); + raw_write_seqcount_t_end(s); } /** * raw_write_seqcount_barrier() - do a seqcount_t write barrier - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * This can be used to provide an ordering guarantee instead of the usual * consistency guarantee. It is one wmb cheaper, because it can collapse @@ -366,7 +680,10 @@ static inline void write_seqcount_end(seqcount_t *s) * WRITE_ONCE(X, false); * } */ -static inline void raw_write_seqcount_barrier(seqcount_t *s) +#define raw_write_seqcount_barrier(s) \ + raw_write_seqcount_t_barrier(__to_seqcount_t(s)) + +static inline void raw_write_seqcount_t_barrier(seqcount_t *s) { kcsan_nestable_atomic_begin(); s->sequence++; @@ -378,12 +695,15 @@ static inline void raw_write_seqcount_barrier(seqcount_t *s) /** * write_seqcount_invalidate() - invalidate in-progress seqcount_t read * side operations - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * After write_seqcount_invalidate, no seqcount_t read side operations * will complete successfully and see data older than this. */ -static inline void write_seqcount_invalidate(seqcount_t *s) +#define write_seqcount_invalidate(s) \ + write_seqcount_t_invalidate(__to_seqcount_t(s)) + +static inline void write_seqcount_t_invalidate(seqcount_t *s) { smp_wmb(); kcsan_nestable_atomic_begin(); @@ -393,7 +713,7 @@ static inline void write_seqcount_invalidate(seqcount_t *s) /** * raw_read_seqcount_latch() - pick even/odd seqcount_t latch data copy - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * Use seqcount_t latching to switch between two storage places protected * by a sequence counter. Doing so allows having interruptible, preemptible, @@ -406,7 +726,10 @@ static inline void write_seqcount_invalidate(seqcount_t *s) * picking which data copy to read. The full counter value must then be * checked with read_seqcount_retry(). */ -static inline int raw_read_seqcount_latch(seqcount_t *s) +#define raw_read_seqcount_latch(s) \ + raw_read_seqcount_t_latch(__to_seqcount_t(s)) + +static inline int raw_read_seqcount_t_latch(seqcount_t *s) { /* Pairs with the first smp_wmb() in raw_write_seqcount_latch() */ int seq = READ_ONCE(s->sequence); /* ^^^ */ @@ -415,7 +738,7 @@ static inline int raw_read_seqcount_latch(seqcount_t *s) /** * raw_write_seqcount_latch() - redirect readers to even/odd copy - * @s: Pointer to seqcount_t + * @s: Pointer to seqcount_t or any of the seqcount_locktype_t variants * * The latch technique is a multiversion concurrency control method that allows * queries during non-atomic modifications. If you can guarantee queries never @@ -494,7 +817,10 @@ static inline int raw_read_seqcount_latch(seqcount_t *s) * When data is a dynamic data structure; one should use regular RCU * patterns to manage the lifetimes of the objects within. */ -static inline void raw_write_seqcount_latch(seqcount_t *s) +#define raw_write_seqcount_latch(s) \ + raw_write_seqcount_t_latch(__to_seqcount_t(s)) + +static inline void raw_write_seqcount_t_latch(seqcount_t *s) { smp_wmb(); /* prior stores before incrementing "sequence" */ s->sequence++; @@ -592,7 +918,7 @@ static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) static inline void write_seqlock(seqlock_t *sl) { spin_lock(&sl->lock); - __write_seqcount_begin(&sl->seqcount); + write_seqcount_t_begin(&sl->seqcount); } /** @@ -604,7 +930,7 @@ static inline void write_seqlock(seqlock_t *sl) */ static inline void write_sequnlock(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + write_seqcount_t_end(&sl->seqcount); spin_unlock(&sl->lock); } @@ -618,7 +944,7 @@ static inline void write_sequnlock(seqlock_t *sl) static inline void write_seqlock_bh(seqlock_t *sl) { spin_lock_bh(&sl->lock); - __write_seqcount_begin(&sl->seqcount); + write_seqcount_t_begin(&sl->seqcount); } /** @@ -631,7 +957,7 @@ static inline void write_seqlock_bh(seqlock_t *sl) */ static inline void write_sequnlock_bh(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + write_seqcount_t_end(&sl->seqcount); spin_unlock_bh(&sl->lock); } @@ -645,7 +971,7 @@ static inline void write_sequnlock_bh(seqlock_t *sl) static inline void write_seqlock_irq(seqlock_t *sl) { spin_lock_irq(&sl->lock); - __write_seqcount_begin(&sl->seqcount); + write_seqcount_t_begin(&sl->seqcount); } /** @@ -657,7 +983,7 @@ static inline void write_seqlock_irq(seqlock_t *sl) */ static inline void write_sequnlock_irq(seqlock_t *sl) { - write_seqcount_end(&sl->seqcount); + write_seqcount_t_end(&sl->seqcount); spin_unlock_irq(&sl->lock); } @@ -666,7 +992,7 @@ static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl) unsigned long flags; spin_lock_irqsave(&sl->lock, flags); - __write_seqcount_begin(&sl->seqcount); + write_seqcount_t_begin(&sl->seqcount); return flags; } @@ -695,13 +1021,13 @@ static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl) static inline void write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags) { - write_seqcount_end(&sl->seqcount); + write_seqcount_t_end(&sl->seqcount); spin_unlock_irqrestore(&sl->lock, flags); } /** * read_seqlock_excl() - begin a seqlock_t locking reader section - * @sl: Pointer to seqlock_t + * @sl: Pointer to seqlock_t * * read_seqlock_excl opens a seqlock_t locking reader critical section. A * locking reader exclusively locks out *both* other writers *and* other -- cgit v1.2.3 From ec8702da570ebb59f38471007bf71359c51b027b Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:16 +0200 Subject: seqlock: Align multi-line macros newline escapes at 72 columns Parent commit, "seqlock: Extend seqcount API with associated locks", introduced a big number of multi-line macros that are newline-escaped at 72 columns. For overall cohesion, align the earlier-existing macros similarly. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-11-a.darwish@linutronix.de --- include/linux/seqlock.h | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 8c16a494c968..b48729988325 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -80,17 +80,18 @@ static inline void __seqcount_init(seqcount_t *s, const char *name, } #ifdef CONFIG_DEBUG_LOCK_ALLOC -# define SEQCOUNT_DEP_MAP_INIT(lockname) \ - .dep_map = { .name = #lockname } \ + +# define SEQCOUNT_DEP_MAP_INIT(lockname) \ + .dep_map = { .name = #lockname } /** * seqcount_init() - runtime initializer for seqcount_t * @s: Pointer to the seqcount_t instance */ -# define seqcount_init(s) \ - do { \ - static struct lock_class_key __key; \ - __seqcount_init((s), #s, &__key); \ +# define seqcount_init(s) \ + do { \ + static struct lock_class_key __key; \ + __seqcount_init((s), #s, &__key); \ } while (0) static inline void seqcount_lockdep_reader_access(const seqcount_t *s) @@ -842,20 +843,20 @@ typedef struct { spinlock_t lock; } seqlock_t; -#define __SEQLOCK_UNLOCKED(lockname) \ - { \ - .seqcount = SEQCNT_ZERO(lockname), \ - .lock = __SPIN_LOCK_UNLOCKED(lockname) \ +#define __SEQLOCK_UNLOCKED(lockname) \ + { \ + .seqcount = SEQCNT_ZERO(lockname), \ + .lock = __SPIN_LOCK_UNLOCKED(lockname) \ } /** * seqlock_init() - dynamic initializer for seqlock_t * @sl: Pointer to the seqlock_t instance */ -#define seqlock_init(sl) \ - do { \ - seqcount_init(&(sl)->seqcount); \ - spin_lock_init(&(sl)->lock); \ +#define seqlock_init(sl) \ + do { \ + seqcount_init(&(sl)->seqcount); \ + spin_lock_init(&(sl)->lock); \ } while (0) /** -- cgit v1.2.3 From 318ce71f3e3ae4108c1665f3860afa8a2a4c9f02 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:17 +0200 Subject: dma-buf: Remove custom seqcount lockdep class key Commit 3c3b177a9369 ("reservation: add support for read-only access using rcu") introduced a sequence counter to manage updates to reservations. Back then, the reservation object initializer reservation_object_init() was always inlined. Having the sequence counter initialization inlined meant that each of the call sites would have a different lockdep class key, which would've broken lockdep's deadlock detection. The aforementioned commit thus introduced, and exported, a custom seqcount lockdep class key and name. The commit 8735f16803f00 ("dma-buf: cleanup reservation_object_init...") transformed the reservation object initializer to a normal non-inlined C function. seqcount_init(), which automatically defines the seqcount lockdep class key and must be called non-inlined, can now be safely used. Remove the seqcount custom lockdep class key, name, and export. Use seqcount_init() inside the dma reservation object initializer. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Sebastian Andrzej Siewior Acked-by: Daniel Vetter Link: https://lkml.kernel.org/r/20200720155530.1173732-12-a.darwish@linutronix.de --- drivers/dma-buf/dma-resv.c | 9 +-------- include/linux/dma-resv.h | 2 -- 2 files changed, 1 insertion(+), 10 deletions(-) (limited to 'include/linux') diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index b45f8514dc82..15efa0c2dacb 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -51,12 +51,6 @@ DEFINE_WD_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class); -struct lock_class_key reservation_seqcount_class; -EXPORT_SYMBOL(reservation_seqcount_class); - -const char reservation_seqcount_string[] = "reservation_seqcount"; -EXPORT_SYMBOL(reservation_seqcount_string); - /** * dma_resv_list_alloc - allocate fence list * @shared_max: number of fences we need space for @@ -135,9 +129,8 @@ subsys_initcall(dma_resv_lockdep); void dma_resv_init(struct dma_resv *obj) { ww_mutex_init(&obj->lock, &reservation_ww_class); + seqcount_init(&obj->seq); - __seqcount_init(&obj->seq, reservation_seqcount_string, - &reservation_seqcount_class); RCU_INIT_POINTER(obj->fence, NULL); RCU_INIT_POINTER(obj->fence_excl, NULL); } diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index ee50d10f052b..a6538ae7d93f 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -46,8 +46,6 @@ #include extern struct ww_class reservation_ww_class; -extern struct lock_class_key reservation_seqcount_class; -extern const char reservation_seqcount_string[]; /** * struct dma_resv_list - a list of shared fences -- cgit v1.2.3 From cd29f22019ec4ab998d2e1e8c831c7c42db4aa7d Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:18 +0200 Subject: dma-buf: Use sequence counter with associated wound/wait mutex A sequence counter write side critical section must be protected by some form of locking to serialize writers. If the serialization primitive is not disabling preemption implicitly, preemption has to be explicitly disabled before entering the sequence counter write side critical section. The dma-buf reservation subsystem uses plain sequence counters to manage updates to reservations. Writer serialization is accomplished through a wound/wait mutex. Acquiring a wound/wait mutex does not disable preemption, so this needs to be done manually before and after the write side critical section. Use the newly-added seqcount_ww_mutex_t instead: - It associates the ww_mutex with the sequence count, which enables lockdep to validate that the write side critical section is properly serialized. - It removes the need to explicitly add preempt_disable/enable() around the write side critical section because the write_begin/end() functions for this new data type automatically do this. If lockdep is disabled this ww_mutex lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Acked-by: Daniel Vetter Link: https://lkml.kernel.org/r/20200720155530.1173732-13-a.darwish@linutronix.de --- drivers/dma-buf/dma-resv.c | 8 +------- drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 -- include/linux/dma-resv.h | 2 +- 3 files changed, 2 insertions(+), 10 deletions(-) (limited to 'include/linux') diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 15efa0c2dacb..a7631352a486 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -129,7 +129,7 @@ subsys_initcall(dma_resv_lockdep); void dma_resv_init(struct dma_resv *obj) { ww_mutex_init(&obj->lock, &reservation_ww_class); - seqcount_init(&obj->seq); + seqcount_ww_mutex_init(&obj->seq, &obj->lock); RCU_INIT_POINTER(obj->fence, NULL); RCU_INIT_POINTER(obj->fence_excl, NULL); @@ -260,7 +260,6 @@ void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence) fobj = dma_resv_get_list(obj); count = fobj->shared_count; - preempt_disable(); write_seqcount_begin(&obj->seq); for (i = 0; i < count; ++i) { @@ -282,7 +281,6 @@ replace: smp_store_mb(fobj->shared_count, count); write_seqcount_end(&obj->seq); - preempt_enable(); dma_fence_put(old); } EXPORT_SYMBOL(dma_resv_add_shared_fence); @@ -309,14 +307,12 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence) if (fence) dma_fence_get(fence); - preempt_disable(); write_seqcount_begin(&obj->seq); /* write_seqcount_begin provides the necessary memory barrier */ RCU_INIT_POINTER(obj->fence_excl, fence); if (old) old->shared_count = 0; write_seqcount_end(&obj->seq); - preempt_enable(); /* inplace update, no shared fences */ while (i--) @@ -394,13 +390,11 @@ retry: src_list = dma_resv_get_list(dst); old = dma_resv_get_excl(dst); - preempt_disable(); write_seqcount_begin(&dst->seq); /* write_seqcount_begin provides the necessary memory barrier */ RCU_INIT_POINTER(dst->fence_excl, new); RCU_INIT_POINTER(dst->fence, dst_list); write_seqcount_end(&dst->seq); - preempt_enable(); dma_resv_list_free(src_list); dma_fence_put(old); diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c index b91b5171270f..ff4b583cb96a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c @@ -258,11 +258,9 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo, new->shared_count = k; /* Install the new fence list, seqcount provides the barriers */ - preempt_disable(); write_seqcount_begin(&resv->seq); RCU_INIT_POINTER(resv->fence, new); write_seqcount_end(&resv->seq); - preempt_enable(); /* Drop the references to the removed fences or move them to ef_list */ for (i = j, k = 0; i < old->shared_count; ++i) { diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index a6538ae7d93f..d44a77e8a7e3 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -69,7 +69,7 @@ struct dma_resv_list { */ struct dma_resv { struct ww_mutex lock; - seqcount_t seq; + seqcount_ww_mutex_t seq; struct dma_fence __rcu *fence_excl; struct dma_resv_list __rcu *fence; -- cgit v1.2.3 From b75058614fdd3140074a640b514f6a0b4d485a2d Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:19 +0200 Subject: sched: tasks: Use sequence counter with associated spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-14-a.darwish@linutronix.de --- include/linux/sched.h | 2 +- init/init_task.c | 3 ++- kernel/fork.c | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 8d1de021b315..9a9d8263962d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1050,7 +1050,7 @@ struct task_struct { /* Protected by ->alloc_lock: */ nodemask_t mems_allowed; /* Seqence number to catch updates: */ - seqcount_t mems_allowed_seq; + seqcount_spinlock_t mems_allowed_seq; int cpuset_mem_spread_rotor; int cpuset_slab_spread_rotor; #endif diff --git a/init/init_task.c b/init/init_task.c index 15089d15010a..94fe3ba1bb60 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -154,7 +154,8 @@ struct task_struct init_task .trc_holdout_list = LIST_HEAD_INIT(init_task.trc_holdout_list), #endif #ifdef CONFIG_CPUSETS - .mems_allowed_seq = SEQCNT_ZERO(init_task.mems_allowed_seq), + .mems_allowed_seq = SEQCNT_SPINLOCK_ZERO(init_task.mems_allowed_seq, + &init_task.alloc_lock), #endif #ifdef CONFIG_RT_MUTEXES .pi_waiters = RB_ROOT_CACHED, diff --git a/kernel/fork.c b/kernel/fork.c index 70d9d0a4de2a..fc72f09a61b2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2032,7 +2032,7 @@ static __latent_entropy struct task_struct *copy_process( #ifdef CONFIG_CPUSETS p->cpuset_mem_spread_rotor = NUMA_NO_NODE; p->cpuset_slab_spread_rotor = NUMA_NO_NODE; - seqcount_init(&p->mems_allowed_seq); + seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock); #endif #ifdef CONFIG_TRACE_IRQFLAGS p->irq_events = 0; -- cgit v1.2.3 From 26475371976c69489d3a8e6c8bbf35afbbc25055 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:24 +0200 Subject: vfs: Use sequence counter with associated spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-19-a.darwish@linutronix.de --- fs/dcache.c | 2 +- fs/fs_struct.c | 4 ++-- include/linux/dcache.h | 2 +- include/linux/fs_struct.h | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/fs/dcache.c b/fs/dcache.c index 361ea7ab30ea..ea0485861d93 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1746,7 +1746,7 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) dentry->d_lockref.count = 1; dentry->d_flags = 0; spin_lock_init(&dentry->d_lock); - seqcount_init(&dentry->d_seq); + seqcount_spinlock_init(&dentry->d_seq, &dentry->d_lock); dentry->d_inode = NULL; dentry->d_parent = dentry; dentry->d_sb = sb; diff --git a/fs/fs_struct.c b/fs/fs_struct.c index ca639ed967b7..04b3f5b9c629 100644 --- a/fs/fs_struct.c +++ b/fs/fs_struct.c @@ -117,7 +117,7 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old) fs->users = 1; fs->in_exec = 0; spin_lock_init(&fs->lock); - seqcount_init(&fs->seq); + seqcount_spinlock_init(&fs->seq, &fs->lock); fs->umask = old->umask; spin_lock(&old->lock); @@ -163,6 +163,6 @@ EXPORT_SYMBOL(current_umask); struct fs_struct init_fs = { .users = 1, .lock = __SPIN_LOCK_UNLOCKED(init_fs.lock), - .seq = SEQCNT_ZERO(init_fs.seq), + .seq = SEQCNT_SPINLOCK_ZERO(init_fs.seq, &init_fs.lock), .umask = 0022, }; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index a81f0c3cf352..65d975bf9390 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -89,7 +89,7 @@ extern struct dentry_stat_t dentry_stat; struct dentry { /* RCU lookup touched fields */ unsigned int d_flags; /* protected by d_lock */ - seqcount_t d_seq; /* per dentry seqlock */ + seqcount_spinlock_t d_seq; /* per dentry seqlock */ struct hlist_bl_node d_hash; /* lookup hash list */ struct dentry *d_parent; /* parent directory */ struct qstr d_name; diff --git a/include/linux/fs_struct.h b/include/linux/fs_struct.h index cf1015abfbf2..783b48dedb72 100644 --- a/include/linux/fs_struct.h +++ b/include/linux/fs_struct.h @@ -9,7 +9,7 @@ struct fs_struct { int users; spinlock_t lock; - seqcount_t seq; + seqcount_spinlock_t seq; int umask; int in_exec; struct path root, pwd; -- cgit v1.2.3 From 5c73b9a2b1b4ecc809a914aa64970157b3d8c936 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:29 +0200 Subject: kvm/eventfd: Use sequence counter with associated spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Acked-by: Paolo Bonzini Link: https://lkml.kernel.org/r/20200720155530.1173732-24-a.darwish@linutronix.de --- include/linux/kvm_irqfd.h | 2 +- virt/kvm/eventfd.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h index dc1da020305b..dac047abdba7 100644 --- a/include/linux/kvm_irqfd.h +++ b/include/linux/kvm_irqfd.h @@ -42,7 +42,7 @@ struct kvm_kernel_irqfd { wait_queue_entry_t wait; /* Update side is protected by irqfds.lock */ struct kvm_kernel_irq_routing_entry irq_entry; - seqcount_t irq_entry_sc; + seqcount_spinlock_t irq_entry_sc; /* Used for level IRQ fast-path */ int gsi; struct work_struct inject; diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index ef7ed916ad4a..d6408bb497dc 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) INIT_LIST_HEAD(&irqfd->list); INIT_WORK(&irqfd->inject, irqfd_inject); INIT_WORK(&irqfd->shutdown, irqfd_shutdown); - seqcount_init(&irqfd->irq_entry_sc); + seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock); f = fdget(args->fd); if (!f.file) { -- cgit v1.2.3 From af5a06b582ec3d7b0160b4faaa65f73d8dcf989f Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Mon, 20 Jul 2020 17:55:30 +0200 Subject: hrtimer: Use sequence counter with associated raw spinlock A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_raw_spinlock_t data type, which allows to associate a raw spinlock with the sequence counter. This enables lockdep to verify that the raw spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-25-a.darwish@linutronix.de --- include/linux/hrtimer.h | 2 +- kernel/time/hrtimer.c | 13 ++++++++++--- 2 files changed, 11 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 15c8ac313678..25993b86ac5c 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -159,7 +159,7 @@ struct hrtimer_clock_base { struct hrtimer_cpu_base *cpu_base; unsigned int index; clockid_t clockid; - seqcount_t seq; + seqcount_raw_spinlock_t seq; struct hrtimer *running; struct timerqueue_head active; ktime_t (*get_time)(void); diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index d89da1c7e005..c4038511d5c9 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -135,7 +135,11 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = { * timer->base->cpu_base */ static struct hrtimer_cpu_base migration_cpu_base = { - .clock_base = { { .cpu_base = &migration_cpu_base, }, }, + .clock_base = { { + .cpu_base = &migration_cpu_base, + .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq, + &migration_cpu_base.lock), + }, }, }; #define migration_base migration_cpu_base.clock_base[0] @@ -1998,8 +2002,11 @@ int hrtimers_prepare_cpu(unsigned int cpu) int i; for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { - cpu_base->clock_base[i].cpu_base = cpu_base; - timerqueue_init_head(&cpu_base->clock_base[i].active); + struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i]; + + clock_b->cpu_base = cpu_base; + seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock); + timerqueue_init_head(&clock_b->active); } cpu_base->cpu = cpu; -- cgit v1.2.3 From e55687fe5c1e4849e5559a0a49199c9ca3fff36e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 23 Jul 2020 11:56:22 +0200 Subject: seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g __SEQ_LOCKDEP() is an expression gate for the seqcount_LOCKNAME_t::lock member. Rename it to be about the member, not the gate condition. Later (PREEMPT_RT) patches will make the member available for !LOCKDEP configs. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/seqlock.h | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index b48729988325..c689abab06c8 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -133,20 +133,20 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s) */ #ifdef CONFIG_LOCKDEP -#define __SEQ_LOCKDEP(expr) expr +#define __SEQ_LOCK(expr) expr #else -#define __SEQ_LOCKDEP(expr) +#define __SEQ_LOCK(expr) #endif #define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) { \ .seqcount = SEQCNT_ZERO(seq_name.seqcount), \ - __SEQ_LOCKDEP(.lock = (assoc_lock)) \ + __SEQ_LOCK(.lock = (assoc_lock)) \ } #define seqcount_locktype_init(s, assoc_lock) \ do { \ seqcount_init(&(s)->seqcount); \ - __SEQ_LOCKDEP((s)->lock = (assoc_lock)); \ + __SEQ_LOCK((s)->lock = (assoc_lock)); \ } while (0) /** @@ -161,7 +161,7 @@ do { \ */ typedef struct seqcount_spinlock { seqcount_t seqcount; - __SEQ_LOCKDEP(spinlock_t *lock); + __SEQ_LOCK(spinlock_t *lock); } seqcount_spinlock_t; /** @@ -192,7 +192,7 @@ typedef struct seqcount_spinlock { */ typedef struct seqcount_raw_spinlock { seqcount_t seqcount; - __SEQ_LOCKDEP(raw_spinlock_t *lock); + __SEQ_LOCK(raw_spinlock_t *lock); } seqcount_raw_spinlock_t; /** @@ -223,7 +223,7 @@ typedef struct seqcount_raw_spinlock { */ typedef struct seqcount_rwlock { seqcount_t seqcount; - __SEQ_LOCKDEP(rwlock_t *lock); + __SEQ_LOCK(rwlock_t *lock); } seqcount_rwlock_t; /** @@ -257,7 +257,7 @@ typedef struct seqcount_rwlock { */ typedef struct seqcount_mutex { seqcount_t seqcount; - __SEQ_LOCKDEP(struct mutex *lock); + __SEQ_LOCK(struct mutex *lock); } seqcount_mutex_t; /** @@ -291,7 +291,7 @@ typedef struct seqcount_mutex { */ typedef struct seqcount_ww_mutex { seqcount_t seqcount; - __SEQ_LOCKDEP(struct ww_mutex *lock); + __SEQ_LOCK(struct ww_mutex *lock); } seqcount_ww_mutex_t; /** @@ -329,7 +329,7 @@ __seqcount_##locktype##_preemptible(seqcount_##locktype##_t *s) \ static inline void \ __seqcount_##locktype##_assert(seqcount_##locktype##_t *s) \ { \ - __SEQ_LOCKDEP(lockdep_assert_held(lockmember)); \ + __SEQ_LOCK(lockdep_assert_held(lockmember)); \ } /* -- cgit v1.2.3 From a8772dccb2ec7b139db1b3ba782ecb12ed92d7c3 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 23 Jul 2020 11:56:49 +0200 Subject: seqlock: Fold seqcount_LOCKNAME_t definition Manual repetition is boring and error prone. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/seqlock.h | 142 +++++++++++++----------------------------------- 1 file changed, 39 insertions(+), 103 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index c689abab06c8..4b259bb4d4b9 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -149,21 +149,6 @@ do { \ __SEQ_LOCK((s)->lock = (assoc_lock)); \ } while (0) -/** - * typedef seqcount_spinlock_t - sequence counter with spinlock associated - * @seqcount: The real sequence counter - * @lock: Pointer to the associated spinlock - * - * A plain sequence counter with external writer synchronization by a - * spinlock. The spinlock is associated to the sequence count in the - * static initializer or init function. This enables lockdep to validate - * that the write side critical section is properly serialized. - */ -typedef struct seqcount_spinlock { - seqcount_t seqcount; - __SEQ_LOCK(spinlock_t *lock); -} seqcount_spinlock_t; - /** * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t * @name: Name of the seqcount_spinlock_t instance @@ -180,21 +165,6 @@ typedef struct seqcount_spinlock { #define seqcount_spinlock_init(s, lock) \ seqcount_locktype_init(s, lock) -/** - * typedef seqcount_raw_spinlock_t - sequence count with raw spinlock associated - * @seqcount: The real sequence counter - * @lock: Pointer to the associated raw spinlock - * - * A plain sequence counter with external writer synchronization by a - * raw spinlock. The raw spinlock is associated to the sequence count in - * the static initializer or init function. This enables lockdep to - * validate that the write side critical section is properly serialized. - */ -typedef struct seqcount_raw_spinlock { - seqcount_t seqcount; - __SEQ_LOCK(raw_spinlock_t *lock); -} seqcount_raw_spinlock_t; - /** * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t * @name: Name of the seqcount_raw_spinlock_t instance @@ -211,21 +181,6 @@ typedef struct seqcount_raw_spinlock { #define seqcount_raw_spinlock_init(s, lock) \ seqcount_locktype_init(s, lock) -/** - * typedef seqcount_rwlock_t - sequence count with rwlock associated - * @seqcount: The real sequence counter - * @lock: Pointer to the associated rwlock - * - * A plain sequence counter with external writer synchronization by a - * rwlock. The rwlock is associated to the sequence count in the static - * initializer or init function. This enables lockdep to validate that - * the write side critical section is properly serialized. - */ -typedef struct seqcount_rwlock { - seqcount_t seqcount; - __SEQ_LOCK(rwlock_t *lock); -} seqcount_rwlock_t; - /** * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t * @name: Name of the seqcount_rwlock_t instance @@ -242,24 +197,6 @@ typedef struct seqcount_rwlock { #define seqcount_rwlock_init(s, lock) \ seqcount_locktype_init(s, lock) -/** - * typedef seqcount_mutex_t - sequence count with mutex associated - * @seqcount: The real sequence counter - * @lock: Pointer to the associated mutex - * - * A plain sequence counter with external writer synchronization by a - * mutex. The mutex is associated to the sequence counter in the static - * initializer or init function. This enables lockdep to validate that - * the write side critical section is properly serialized. - * - * The write side API functions write_seqcount_begin()/end() automatically - * disable and enable preemption when used with seqcount_mutex_t. - */ -typedef struct seqcount_mutex { - seqcount_t seqcount; - __SEQ_LOCK(struct mutex *lock); -} seqcount_mutex_t; - /** * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t * @name: Name of the seqcount_mutex_t instance @@ -276,24 +213,6 @@ typedef struct seqcount_mutex { #define seqcount_mutex_init(s, lock) \ seqcount_locktype_init(s, lock) -/** - * typedef seqcount_ww_mutex_t - sequence count with ww_mutex associated - * @seqcount: The real sequence counter - * @lock: Pointer to the associated ww_mutex - * - * A plain sequence counter with external writer synchronization by a - * ww_mutex. The ww_mutex is associated to the sequence counter in the static - * initializer or init function. This enables lockdep to validate that - * the write side critical section is properly serialized. - * - * The write side API functions write_seqcount_begin()/end() automatically - * disable and enable preemption when used with seqcount_ww_mutex_t. - */ -typedef struct seqcount_ww_mutex { - seqcount_t seqcount; - __SEQ_LOCK(struct ww_mutex *lock); -} seqcount_ww_mutex_t; - /** * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t * @name: Name of the seqcount_ww_mutex_t instance @@ -310,30 +229,50 @@ typedef struct seqcount_ww_mutex { #define seqcount_ww_mutex_init(s, lock) \ seqcount_locktype_init(s, lock) -/* - * @preempt: Is the associated write serialization lock preemtpible? +/** + * typedef seqcount_LOCKNAME_t - sequence counter with spinlock associated + * @seqcount: The real sequence counter + * @lock: Pointer to the associated spinlock + * + * A plain sequence counter with external writer synchronization by a + * spinlock. The spinlock is associated to the sequence count in the + * static initializer or init function. This enables lockdep to validate + * that the write side critical section is properly serialized. */ -#define SEQCOUNT_LOCKTYPE(locktype, preempt, lockmember) \ -static inline seqcount_t * \ -__seqcount_##locktype##_ptr(seqcount_##locktype##_t *s) \ + +/* + * SEQCOUNT_LOCKTYPE() - Instantiate seqcount_LOCKNAME_t and helpers + * @locktype: actual typename + * @lockname: name + * @preemptible: preemptibility of above locktype + * @lockmember: argument for lockdep_assert_held() + */ +#define SEQCOUNT_LOCKTYPE(locktype, lockname, preemptible, lockmember) \ +typedef struct seqcount_##lockname { \ + seqcount_t seqcount; \ + __SEQ_LOCK(locktype *lock); \ +} seqcount_##lockname##_t; \ + \ +static __always_inline seqcount_t * \ +__seqcount_##lockname##_ptr(seqcount_##lockname##_t *s) \ { \ return &s->seqcount; \ } \ \ -static inline bool \ -__seqcount_##locktype##_preemptible(seqcount_##locktype##_t *s) \ +static __always_inline bool \ +__seqcount_##lockname##_preemptible(seqcount_##lockname##_t *s) \ { \ - return preempt; \ + return preemptible; \ } \ \ -static inline void \ -__seqcount_##locktype##_assert(seqcount_##locktype##_t *s) \ +static __always_inline void \ +__seqcount_##lockname##_assert(seqcount_##lockname##_t *s) \ { \ __SEQ_LOCK(lockdep_assert_held(lockmember)); \ } /* - * Similar hooks, but for plain seqcount_t + * __seqprop() for seqcount_t */ static inline seqcount_t *__seqcount_ptr(seqcount_t *s) @@ -351,17 +290,14 @@ static inline void __seqcount_assert(seqcount_t *s) lockdep_assert_preemption_disabled(); } -/* - * @s: Pointer to seqcount_locktype_t, generated hooks first parameter. - */ -SEQCOUNT_LOCKTYPE(raw_spinlock, false, s->lock) -SEQCOUNT_LOCKTYPE(spinlock, false, s->lock) -SEQCOUNT_LOCKTYPE(rwlock, false, s->lock) -SEQCOUNT_LOCKTYPE(mutex, true, s->lock) -SEQCOUNT_LOCKTYPE(ww_mutex, true, &s->lock->base) - -#define __seqprop_case(s, locktype, prop) \ - seqcount_##locktype##_t: __seqcount_##locktype##_##prop((void *)(s)) +SEQCOUNT_LOCKTYPE(raw_spinlock_t, raw_spinlock, false, s->lock) +SEQCOUNT_LOCKTYPE(spinlock_t, spinlock, false, s->lock) +SEQCOUNT_LOCKTYPE(rwlock_t, rwlock, false, s->lock) +SEQCOUNT_LOCKTYPE(struct mutex, mutex, true, s->lock) +SEQCOUNT_LOCKTYPE(struct ww_mutex, ww_mutex, true, &s->lock->base) + +#define __seqprop_case(s, lockname, prop) \ + seqcount_##lockname##_t: __seqcount_##lockname##_##prop((void *)(s)) #define __seqprop(s, prop) _Generic(*(s), \ seqcount_t: __seqcount_##prop((void *)(s)), \ -- cgit v1.2.3 From e4e9ab3f9f91ad3b88d12363f890e8ad9b59b645 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 23 Jul 2020 12:00:53 +0200 Subject: seqlock: Fold seqcount_LOCKNAME_init() definition Manual repetition is boring and error prone. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/seqlock.h | 61 ++++++++++++------------------------------------- 1 file changed, 14 insertions(+), 47 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 4b259bb4d4b9..501ff47d1e8e 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -143,12 +143,6 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s) __SEQ_LOCK(.lock = (assoc_lock)) \ } -#define seqcount_locktype_init(s, assoc_lock) \ -do { \ - seqcount_init(&(s)->seqcount); \ - __SEQ_LOCK((s)->lock = (assoc_lock)); \ -} while (0) - /** * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t * @name: Name of the seqcount_spinlock_t instance @@ -157,14 +151,6 @@ do { \ #define SEQCNT_SPINLOCK_ZERO(name, lock) \ SEQCOUNT_LOCKTYPE_ZERO(name, lock) -/** - * seqcount_spinlock_init - runtime initializer for seqcount_spinlock_t - * @s: Pointer to the seqcount_spinlock_t instance - * @lock: Pointer to the associated spinlock - */ -#define seqcount_spinlock_init(s, lock) \ - seqcount_locktype_init(s, lock) - /** * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t * @name: Name of the seqcount_raw_spinlock_t instance @@ -173,14 +159,6 @@ do { \ #define SEQCNT_RAW_SPINLOCK_ZERO(name, lock) \ SEQCOUNT_LOCKTYPE_ZERO(name, lock) -/** - * seqcount_raw_spinlock_init - runtime initializer for seqcount_raw_spinlock_t - * @s: Pointer to the seqcount_raw_spinlock_t instance - * @lock: Pointer to the associated raw_spinlock - */ -#define seqcount_raw_spinlock_init(s, lock) \ - seqcount_locktype_init(s, lock) - /** * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t * @name: Name of the seqcount_rwlock_t instance @@ -189,14 +167,6 @@ do { \ #define SEQCNT_RWLOCK_ZERO(name, lock) \ SEQCOUNT_LOCKTYPE_ZERO(name, lock) -/** - * seqcount_rwlock_init - runtime initializer for seqcount_rwlock_t - * @s: Pointer to the seqcount_rwlock_t instance - * @lock: Pointer to the associated rwlock - */ -#define seqcount_rwlock_init(s, lock) \ - seqcount_locktype_init(s, lock) - /** * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t * @name: Name of the seqcount_mutex_t instance @@ -205,14 +175,6 @@ do { \ #define SEQCNT_MUTEX_ZERO(name, lock) \ SEQCOUNT_LOCKTYPE_ZERO(name, lock) -/** - * seqcount_mutex_init - runtime initializer for seqcount_mutex_t - * @s: Pointer to the seqcount_mutex_t instance - * @lock: Pointer to the associated mutex - */ -#define seqcount_mutex_init(s, lock) \ - seqcount_locktype_init(s, lock) - /** * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t * @name: Name of the seqcount_ww_mutex_t instance @@ -222,15 +184,7 @@ do { \ SEQCOUNT_LOCKTYPE_ZERO(name, lock) /** - * seqcount_ww_mutex_init - runtime initializer for seqcount_ww_mutex_t - * @s: Pointer to the seqcount_ww_mutex_t instance - * @lock: Pointer to the associated ww_mutex - */ -#define seqcount_ww_mutex_init(s, lock) \ - seqcount_locktype_init(s, lock) - -/** - * typedef seqcount_LOCKNAME_t - sequence counter with spinlock associated + * typedef seqcount_LOCKNAME_t - sequence counter with LOCKTYPR associated * @seqcount: The real sequence counter * @lock: Pointer to the associated spinlock * @@ -240,6 +194,12 @@ do { \ * that the write side critical section is properly serialized. */ +/** + * seqcount_LOCKNAME_init() - runtime initializer for seqcount_LOCKNAME_t + * @s: Pointer to the seqcount_LOCKNAME_t instance + * @lock: Pointer to the associated LOCKTYPE + */ + /* * SEQCOUNT_LOCKTYPE() - Instantiate seqcount_LOCKNAME_t and helpers * @locktype: actual typename @@ -253,6 +213,13 @@ typedef struct seqcount_##lockname { \ __SEQ_LOCK(locktype *lock); \ } seqcount_##lockname##_t; \ \ +static __always_inline void \ +seqcount_##lockname##_init(seqcount_##lockname##_t *s, locktype *lock) \ +{ \ + seqcount_init(&s->seqcount); \ + __SEQ_LOCK(s->lock = lock); \ +} \ + \ static __always_inline seqcount_t * \ __seqcount_##lockname##_ptr(seqcount_##lockname##_t *s) \ { \ -- cgit v1.2.3 From 0efc94c5d15c3da0a69543d86ad2180f39256ed6 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 23 Jul 2020 12:03:13 +0200 Subject: seqcount: Compress SEQCNT_LOCKNAME_ZERO() Less is more. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/seqlock.h | 63 ++++++++++++++----------------------------------- 1 file changed, 18 insertions(+), 45 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 501ff47d1e8e..251dcd6f5cd8 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -138,51 +138,6 @@ static inline void seqcount_lockdep_reader_access(const seqcount_t *s) #define __SEQ_LOCK(expr) #endif -#define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) { \ - .seqcount = SEQCNT_ZERO(seq_name.seqcount), \ - __SEQ_LOCK(.lock = (assoc_lock)) \ -} - -/** - * SEQCNT_SPINLOCK_ZERO - static initializer for seqcount_spinlock_t - * @name: Name of the seqcount_spinlock_t instance - * @lock: Pointer to the associated spinlock - */ -#define SEQCNT_SPINLOCK_ZERO(name, lock) \ - SEQCOUNT_LOCKTYPE_ZERO(name, lock) - -/** - * SEQCNT_RAW_SPINLOCK_ZERO - static initializer for seqcount_raw_spinlock_t - * @name: Name of the seqcount_raw_spinlock_t instance - * @lock: Pointer to the associated raw_spinlock - */ -#define SEQCNT_RAW_SPINLOCK_ZERO(name, lock) \ - SEQCOUNT_LOCKTYPE_ZERO(name, lock) - -/** - * SEQCNT_RWLOCK_ZERO - static initializer for seqcount_rwlock_t - * @name: Name of the seqcount_rwlock_t instance - * @lock: Pointer to the associated rwlock - */ -#define SEQCNT_RWLOCK_ZERO(name, lock) \ - SEQCOUNT_LOCKTYPE_ZERO(name, lock) - -/** - * SEQCNT_MUTEX_ZERO - static initializer for seqcount_mutex_t - * @name: Name of the seqcount_mutex_t instance - * @lock: Pointer to the associated mutex - */ -#define SEQCNT_MUTEX_ZERO(name, lock) \ - SEQCOUNT_LOCKTYPE_ZERO(name, lock) - -/** - * SEQCNT_WW_MUTEX_ZERO - static initializer for seqcount_ww_mutex_t - * @name: Name of the seqcount_ww_mutex_t instance - * @lock: Pointer to the associated ww_mutex - */ -#define SEQCNT_WW_MUTEX_ZERO(name, lock) \ - SEQCOUNT_LOCKTYPE_ZERO(name, lock) - /** * typedef seqcount_LOCKNAME_t - sequence counter with LOCKTYPR associated * @seqcount: The real sequence counter @@ -263,6 +218,24 @@ SEQCOUNT_LOCKTYPE(rwlock_t, rwlock, false, s->lock) SEQCOUNT_LOCKTYPE(struct mutex, mutex, true, s->lock) SEQCOUNT_LOCKTYPE(struct ww_mutex, ww_mutex, true, &s->lock->base) +/** + * SEQCNT_LOCKNAME_ZERO - static initializer for seqcount_LOCKNAME_t + * @name: Name of the seqcount_LOCKNAME_t instance + * @lock: Pointer to the associated LOCKTYPE + */ + +#define SEQCOUNT_LOCKTYPE_ZERO(seq_name, assoc_lock) { \ + .seqcount = SEQCNT_ZERO(seq_name.seqcount), \ + __SEQ_LOCK(.lock = (assoc_lock)) \ +} + +#define SEQCNT_SPINLOCK_ZERO(name, lock) SEQCOUNT_LOCKTYPE_ZERO(name, lock) +#define SEQCNT_RAW_SPINLOCK_ZERO(name, lock) SEQCOUNT_LOCKTYPE_ZERO(name, lock) +#define SEQCNT_RWLOCK_ZERO(name, lock) SEQCOUNT_LOCKTYPE_ZERO(name, lock) +#define SEQCNT_MUTEX_ZERO(name, lock) SEQCOUNT_LOCKTYPE_ZERO(name, lock) +#define SEQCNT_WW_MUTEX_ZERO(name, lock) SEQCOUNT_LOCKTYPE_ZERO(name, lock) + + #define __seqprop_case(s, lockname, prop) \ seqcount_##lockname##_t: __seqcount_##lockname##_##prop((void *)(s)) -- cgit v1.2.3 From b5e6a027bd327daa679ca55182a920659e2cbb90 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 23 Jul 2020 12:11:49 +0200 Subject: seqcount: More consistent seqprop names Attempt uniformity and brevity. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/seqlock.h | 52 ++++++++++++++++++++++++------------------------- 1 file changed, 26 insertions(+), 26 deletions(-) (limited to 'include/linux') diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 251dcd6f5cd8..a076f783aa36 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -247,9 +247,9 @@ SEQCOUNT_LOCKTYPE(struct ww_mutex, ww_mutex, true, &s->lock->base) __seqprop_case((s), mutex, prop), \ __seqprop_case((s), ww_mutex, prop)) -#define __to_seqcount_t(s) __seqprop(s, ptr) -#define __associated_lock_exists_and_is_preemptible(s) __seqprop(s, preemptible) -#define __assert_write_section_is_protected(s) __seqprop(s, assert) +#define __seqcount_ptr(s) __seqprop(s, ptr) +#define __seqcount_lock_preemptible(s) __seqprop(s, preemptible) +#define __seqcount_assert_lock_held(s) __seqprop(s, assert) /** * __read_seqcount_begin() - begin a seqcount_t read section w/o barrier @@ -266,7 +266,7 @@ SEQCOUNT_LOCKTYPE(struct ww_mutex, ww_mutex, true, &s->lock->base) * Return: count to be passed to read_seqcount_retry() */ #define __read_seqcount_begin(s) \ - __read_seqcount_t_begin(__to_seqcount_t(s)) + __read_seqcount_t_begin(__seqcount_ptr(s)) static inline unsigned __read_seqcount_t_begin(const seqcount_t *s) { @@ -289,7 +289,7 @@ repeat: * Return: count to be passed to read_seqcount_retry() */ #define raw_read_seqcount_begin(s) \ - raw_read_seqcount_t_begin(__to_seqcount_t(s)) + raw_read_seqcount_t_begin(__seqcount_ptr(s)) static inline unsigned raw_read_seqcount_t_begin(const seqcount_t *s) { @@ -305,7 +305,7 @@ static inline unsigned raw_read_seqcount_t_begin(const seqcount_t *s) * Return: count to be passed to read_seqcount_retry() */ #define read_seqcount_begin(s) \ - read_seqcount_t_begin(__to_seqcount_t(s)) + read_seqcount_t_begin(__seqcount_ptr(s)) static inline unsigned read_seqcount_t_begin(const seqcount_t *s) { @@ -325,7 +325,7 @@ static inline unsigned read_seqcount_t_begin(const seqcount_t *s) * Return: count to be passed to read_seqcount_retry() */ #define raw_read_seqcount(s) \ - raw_read_seqcount_t(__to_seqcount_t(s)) + raw_read_seqcount_t(__seqcount_ptr(s)) static inline unsigned raw_read_seqcount_t(const seqcount_t *s) { @@ -353,7 +353,7 @@ static inline unsigned raw_read_seqcount_t(const seqcount_t *s) * Return: count to be passed to read_seqcount_retry() */ #define raw_seqcount_begin(s) \ - raw_seqcount_t_begin(__to_seqcount_t(s)) + raw_seqcount_t_begin(__seqcount_ptr(s)) static inline unsigned raw_seqcount_t_begin(const seqcount_t *s) { @@ -380,7 +380,7 @@ static inline unsigned raw_seqcount_t_begin(const seqcount_t *s) * Return: true if a read section retry is required, else false */ #define __read_seqcount_retry(s, start) \ - __read_seqcount_t_retry(__to_seqcount_t(s), start) + __read_seqcount_t_retry(__seqcount_ptr(s), start) static inline int __read_seqcount_t_retry(const seqcount_t *s, unsigned start) { @@ -400,7 +400,7 @@ static inline int __read_seqcount_t_retry(const seqcount_t *s, unsigned start) * Return: true if a read section retry is required, else false */ #define read_seqcount_retry(s, start) \ - read_seqcount_t_retry(__to_seqcount_t(s), start) + read_seqcount_t_retry(__seqcount_ptr(s), start) static inline int read_seqcount_t_retry(const seqcount_t *s, unsigned start) { @@ -414,10 +414,10 @@ static inline int read_seqcount_t_retry(const seqcount_t *s, unsigned start) */ #define raw_write_seqcount_begin(s) \ do { \ - if (__associated_lock_exists_and_is_preemptible(s)) \ + if (__seqcount_lock_preemptible(s)) \ preempt_disable(); \ \ - raw_write_seqcount_t_begin(__to_seqcount_t(s)); \ + raw_write_seqcount_t_begin(__seqcount_ptr(s)); \ } while (0) static inline void raw_write_seqcount_t_begin(seqcount_t *s) @@ -433,9 +433,9 @@ static inline void raw_write_seqcount_t_begin(seqcount_t *s) */ #define raw_write_seqcount_end(s) \ do { \ - raw_write_seqcount_t_end(__to_seqcount_t(s)); \ + raw_write_seqcount_t_end(__seqcount_ptr(s)); \ \ - if (__associated_lock_exists_and_is_preemptible(s)) \ + if (__seqcount_lock_preemptible(s)) \ preempt_enable(); \ } while (0) @@ -456,12 +456,12 @@ static inline void raw_write_seqcount_t_end(seqcount_t *s) */ #define write_seqcount_begin_nested(s, subclass) \ do { \ - __assert_write_section_is_protected(s); \ + __seqcount_assert_lock_held(s); \ \ - if (__associated_lock_exists_and_is_preemptible(s)) \ + if (__seqcount_lock_preemptible(s)) \ preempt_disable(); \ \ - write_seqcount_t_begin_nested(__to_seqcount_t(s), subclass); \ + write_seqcount_t_begin_nested(__seqcount_ptr(s), subclass); \ } while (0) static inline void write_seqcount_t_begin_nested(seqcount_t *s, int subclass) @@ -483,12 +483,12 @@ static inline void write_seqcount_t_begin_nested(seqcount_t *s, int subclass) */ #define write_seqcount_begin(s) \ do { \ - __assert_write_section_is_protected(s); \ + __seqcount_assert_lock_held(s); \ \ - if (__associated_lock_exists_and_is_preemptible(s)) \ + if (__seqcount_lock_preemptible(s)) \ preempt_disable(); \ \ - write_seqcount_t_begin(__to_seqcount_t(s)); \ + write_seqcount_t_begin(__seqcount_ptr(s)); \ } while (0) static inline void write_seqcount_t_begin(seqcount_t *s) @@ -504,9 +504,9 @@ static inline void write_seqcount_t_begin(seqcount_t *s) */ #define write_seqcount_end(s) \ do { \ - write_seqcount_t_end(__to_seqcount_t(s)); \ + write_seqcount_t_end(__seqcount_ptr(s)); \ \ - if (__associated_lock_exists_and_is_preemptible(s)) \ + if (__seqcount_lock_preemptible(s)) \ preempt_enable(); \ } while (0) @@ -558,7 +558,7 @@ static inline void write_seqcount_t_end(seqcount_t *s) * } */ #define raw_write_seqcount_barrier(s) \ - raw_write_seqcount_t_barrier(__to_seqcount_t(s)) + raw_write_seqcount_t_barrier(__seqcount_ptr(s)) static inline void raw_write_seqcount_t_barrier(seqcount_t *s) { @@ -578,7 +578,7 @@ static inline void raw_write_seqcount_t_barrier(seqcount_t *s) * will complete successfully and see data older than this. */ #define write_seqcount_invalidate(s) \ - write_seqcount_t_invalidate(__to_seqcount_t(s)) + write_seqcount_t_invalidate(__seqcount_ptr(s)) static inline void write_seqcount_t_invalidate(seqcount_t *s) { @@ -604,7 +604,7 @@ static inline void write_seqcount_t_invalidate(seqcount_t *s) * checked with read_seqcount_retry(). */ #define raw_read_seqcount_latch(s) \ - raw_read_seqcount_t_latch(__to_seqcount_t(s)) + raw_read_seqcount_t_latch(__seqcount_ptr(s)) static inline int raw_read_seqcount_t_latch(seqcount_t *s) { @@ -695,7 +695,7 @@ static inline int raw_read_seqcount_t_latch(seqcount_t *s) * patterns to manage the lifetimes of the objects within. */ #define raw_write_seqcount_latch(s) \ - raw_write_seqcount_t_latch(__to_seqcount_t(s)) + raw_write_seqcount_t_latch(__seqcount_ptr(s)) static inline void raw_write_seqcount_t_latch(seqcount_t *s) { -- cgit v1.2.3 From 0cd39f4600ed4de859383018eb10f0f724900e1b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 6 Aug 2020 14:35:11 +0200 Subject: locking/seqlock, headers: Untangle the spaghetti monster By using lockdep_assert_*() from seqlock.h, the spaghetti monster attacked. Attack back by reducing seqlock.h dependencies from two key high level headers: - : -Remove - : -Remove - : +Add The price was to add it to sched.h ... Core header fallout, we add direct header dependencies instead of gaining them parasitically from higher level headers: - : +Add - : +Add - : +Add - : +Add - : +Add - : +Add Arch headers fallout: - PARISC: : +Add - SH: : +Add - SPARC: : +Add - SPARC: : +Add , -Remove - X86: : +Add -Remove There's also a bunch of parasitic header dependency fallout in .c files, not listed separately. [ mingo: Extended the changelog, split up & fixed the original patch. ] Co-developed-by: Ingo Molnar Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net --- arch/sh/include/asm/io.h | 1 + arch/sh/kernel/machvec.c | 1 + arch/sparc/include/asm/timer_64.h | 1 + arch/sparc/include/asm/vvar.h | 3 ++- arch/sparc/kernel/vdso.c | 1 - arch/x86/include/asm/fixmap.h | 2 +- arch/x86/kernel/apic/apic_noop.c | 1 + arch/x86/kernel/apic/hw_nmi.c | 1 + arch/x86/kernel/apic/probe_64.c | 1 + arch/x86/kernel/cpu/amd.c | 1 + arch/x86/kernel/cpu/common.c | 1 + arch/x86/kernel/cpu/hygon.c | 1 + arch/x86/kernel/cpu/intel.c | 1 + arch/x86/kernel/jailhouse.c | 1 + arch/x86/kernel/tsc_msr.c | 1 + arch/x86/mm/init_32.c | 1 + arch/x86/xen/apic.c | 1 + arch/x86/xen/smp_hvm.c | 1 + arch/x86/xen/suspend_pv.c | 4 ++-- include/linux/dynamic_queue_limits.h | 2 ++ include/linux/hrtimer.h | 1 + include/linux/ktime.h | 1 + include/linux/lockdep.h | 1 + include/linux/mutex.h | 11 +++++++++++ include/linux/sched.h | 1 + include/linux/seqlock.h | 1 - include/linux/time.h | 1 - include/linux/videodev2.h | 1 + include/linux/ww_mutex.h | 8 -------- 29 files changed, 38 insertions(+), 15 deletions(-) (limited to 'include/linux') diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h index 26f0f9b4658b..ec587b583822 100644 --- a/arch/sh/include/asm/io.h +++ b/arch/sh/include/asm/io.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include diff --git a/arch/sh/kernel/machvec.c b/arch/sh/kernel/machvec.c index beadbbdb4486..76bd8955d4fe 100644 --- a/arch/sh/kernel/machvec.c +++ b/arch/sh/kernel/machvec.c @@ -15,6 +15,7 @@ #include #include #include +#include #define MV_NAME_SIZE 32 diff --git a/arch/sparc/include/asm/timer_64.h b/arch/sparc/include/asm/timer_64.h index c7e4fb601a57..dcfad4613e18 100644 --- a/arch/sparc/include/asm/timer_64.h +++ b/arch/sparc/include/asm/timer_64.h @@ -7,6 +7,7 @@ #ifndef _SPARC64_TIMER_H #define _SPARC64_TIMER_H +#include #include #include diff --git a/arch/sparc/include/asm/vvar.h b/arch/sparc/include/asm/vvar.h index 0289503d1cb0..6eaf5cfcaae1 100644 --- a/arch/sparc/include/asm/vvar.h +++ b/arch/sparc/include/asm/vvar.h @@ -6,7 +6,8 @@ #define _ASM_SPARC_VVAR_DATA_H #include -#include +#include +#include #include #include diff --git a/arch/sparc/kernel/vdso.c b/arch/sparc/kernel/vdso.c index 58880662b271..0e27437eb97b 100644 --- a/arch/sparc/kernel/vdso.c +++ b/arch/sparc/kernel/vdso.c @@ -7,7 +7,6 @@ * a different vsyscall implementation for Linux/IA32 and for the name. */ -#include #include #include diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index b9527a54db99..0f0dd645b594 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -26,9 +26,9 @@ #ifndef __ASSEMBLY__ #include -#include #include #include +#include #ifdef CONFIG_X86_32 #include #include diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c index 98c9bb75d185..780c702969b7 100644 --- a/arch/x86/kernel/apic/apic_noop.c +++ b/arch/x86/kernel/apic/apic_noop.c @@ -10,6 +10,7 @@ * like self-ipi, etc... */ #include +#include #include diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c index d1fc62a67320..34a992e275ef 100644 --- a/arch/x86/kernel/apic/hw_nmi.c +++ b/arch/x86/kernel/apic/hw_nmi.c @@ -9,6 +9,7 @@ * Bits copied from original nmi.c file * */ +#include #include #include diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c index 29f0e0984557..bd3835d6b535 100644 --- a/arch/x86/kernel/apic/probe_64.c +++ b/arch/x86/kernel/apic/probe_64.c @@ -8,6 +8,7 @@ * Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and * James Cleverdon. */ +#include #include #include "local.h" diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index d4806eac9325..dcc3d943c68f 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 95c090a45b4b..52b565016eb1 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c index 4e28c1fc8749..ac6c30e5801d 100644 --- a/arch/x86/kernel/cpu/hygon.c +++ b/arch/x86/kernel/cpu/hygon.c @@ -10,6 +10,7 @@ #include #include +#include #include #include #include diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 0ab48f1cdf84..6eb42d7a3dfd 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -23,6 +23,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c index 2caf5b990bf6..4eb8f2d19a87 100644 --- a/arch/x86/kernel/jailhouse.c +++ b/arch/x86/kernel/jailhouse.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c index 4fec6f3a1858..46c72f2ec32f 100644 --- a/arch/x86/kernel/tsc_msr.c +++ b/arch/x86/kernel/tsc_msr.c @@ -7,6 +7,7 @@ */ #include +#include #include #include diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 8b4afad84f4a..d46a5cf6ccb0 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -52,6 +52,7 @@ #include #include #include +#include #include "mm_internal.h" diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c index 2df7d089ad54..1aff4ae65655 100644 --- a/arch/x86/xen/apic.c +++ b/arch/x86/xen/apic.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include diff --git a/arch/x86/xen/smp_hvm.c b/arch/x86/xen/smp_hvm.c index f8d39440b292..f5e7db4f82ab 100644 --- a/arch/x86/xen/smp_hvm.c +++ b/arch/x86/xen/smp_hvm.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include diff --git a/arch/x86/xen/suspend_pv.c b/arch/x86/xen/suspend_pv.c index 8303b58c79a9..cae9660f4c67 100644 --- a/arch/x86/xen/suspend_pv.c +++ b/arch/x86/xen/suspend_pv.c @@ -1,11 +1,11 @@ // SPDX-License-Identifier: GPL-2.0 #include -#include - #include #include +#include + #include "xen-ops.h" void xen_pv_pre_suspend(void) diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h index 99fc06f0afc1..407c2f281b64 100644 --- a/include/linux/dynamic_queue_limits.h +++ b/include/linux/dynamic_queue_limits.h @@ -38,6 +38,8 @@ #ifdef __KERNEL__ +#include + struct dql { /* Fields accessed in enqueue path (dql_queued) */ unsigned int num_queued; /* Total ever queued */ diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 25993b86ac5c..107cedd7019a 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include diff --git a/include/linux/ktime.h b/include/linux/ktime.h index 42d2e6ac35f2..a12b5523cc18 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -23,6 +23,7 @@ #include #include +#include /* Nanosecond scalar representation for kernel time values */ typedef s64 ktime_t; diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 39a35699d0d6..62a382d1845b 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -11,6 +11,7 @@ #define __LINUX_LOCKDEP_H #include +#include #include struct task_struct; diff --git a/include/linux/mutex.h b/include/linux/mutex.h index ae197cc00cc8..dcd185cbfe79 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -65,6 +65,17 @@ struct mutex { #endif }; +struct ww_class; +struct ww_acquire_ctx; + +struct ww_mutex { + struct mutex base; + struct ww_acquire_ctx *ctx; +#ifdef CONFIG_DEBUG_MUTEXES + struct ww_class *ww_class; +#endif +}; + /* * This is the control structure for tasks blocked on mutex, * which resides on the blocked task's kernel stack: diff --git a/include/linux/sched.h b/include/linux/sched.h index 9a9d8263962d..7c7a9499d7bc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -31,6 +31,7 @@ #include #include #include +#include #include /* task_struct member predeclarations (sorted alphabetically): */ diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index a076f783aa36..962d9768945f 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -19,7 +19,6 @@ #include #include #include -#include #include diff --git a/include/linux/time.h b/include/linux/time.h index 4c325bf44ce0..b142cb5f5a53 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -3,7 +3,6 @@ #define _LINUX_TIME_H # include -# include # include # include diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h index 16c0ed6c50a7..219037f4c08d 100644 --- a/include/linux/videodev2.h +++ b/include/linux/videodev2.h @@ -57,6 +57,7 @@ #define __LINUX_VIDEODEV2_H #include /* need struct timeval */ +#include #include #endif /* __LINUX_VIDEODEV2_H */ diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h index d7554252404c..850424e5d030 100644 --- a/include/linux/ww_mutex.h +++ b/include/linux/ww_mutex.h @@ -48,14 +48,6 @@ struct ww_acquire_ctx { #endif }; -struct ww_mutex { - struct mutex base; - struct ww_acquire_ctx *ctx; -#ifdef CONFIG_DEBUG_MUTEXES - struct ww_class *ww_class; -#endif -}; - #ifdef CONFIG_DEBUG_LOCK_ALLOC # define __WW_CLASS_MUTEX_INITIALIZER(lockname, class) \ , .ww_class = class -- cgit v1.2.3