user/sven/linux.git/Documentation/locking, branch v5.9.8

Documentation/locking/locktypes: fix local_locks documentation

2020-08-24T23:18:51Z

Fix issues with local_locks documentation: - fix function names, local_lock.h has local_unlock_irqrestore(), not local_lock_irqrestore() - fix mapping table, local_unlock_irqrestore() maps to local_irq_restore(), not _save() Signed-off-by: Marta Rybczynska Acked-by: Will Deacon Link: https://lore.kernel.org/r/CAApg2=SKxQ3Sqwj6TZnV-0x0cKLXFKDaPvXT4N15MPDMKq724g@mail.gmail.com Signed-off-by: Jonathan Corbet

Merge tag 'docs-5.9-2' of git://git.lwn.net/linux

2020-08-13T20:57:45Z

Pull documentation fixes from Jonathan Corbet: "A handful of obvious fixes that wandered in during the merge window" * tag 'docs-5.9-2' of git://git.lwn.net/linux: Documentation/locking/locktypes: fix the typo doc/zh_CN: resolve undefined label warning in admin-guide index doc/zh_CN: fix title heading markup in admin-guide cpu-load docs: remove the 2.6 "Upgrading I2C Drivers" guide docs: Correct the release date of 5.2 stable mailmap: Update comments for with format and more detalis docs: cdrom: Fix a typo and rst markup Doc: admin-guide: use correct legends in kernel-parameters.txt Documentation/features: refresh RISC-V arch support files documentation: coccinelle: Improve command example for make C={1,2} Core-api: Documentation: Replace deprecated :c:func: Usage Dev-tools: Documentation: Replace deprecated :c:func: Usage Filesystems: Documentation: Replace deprecated :c:func: Usage docs: trace: fix a typo

Documentation/locking/locktypes: fix the typo

2020-08-13T20:47:38Z

We have three categories locks, not two. Signed-off-by: Huang Shijie Acked-by: Will Deacon Link: https://lore.kernel.org/r/20200813060220.18199-1-sjhuang@iluvatar.ai Signed-off-by: Jonathan Corbet

Merge tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-11T02:07:44Z

Pull locking updates from Thomas Gleixner: "A set of locking fixes and updates: - Untangle the header spaghetti which causes build failures in various situations caused by the lockdep additions to seqcount to validate that the write side critical sections are non-preemptible. - The seqcount associated lock debug addons which were blocked by the above fallout. seqcount writers contrary to seqlock writers must be externally serialized, which usually happens via locking - except for strict per CPU seqcounts. As the lock is not part of the seqcount, lockdep cannot validate that the lock is held. This new debug mechanism adds the concept of associated locks. sequence count has now lock type variants and corresponding initializers which take a pointer to the associated lock used for writer serialization. If lockdep is enabled the pointer is stored and write_seqcount_begin() has a lockdep assertion to validate that the lock is held. Aside of the type and the initializer no other code changes are required at the seqcount usage sites. The rest of the seqcount API is unchanged and determines the type at compile time with the help of _Generic which is possible now that the minimal GCC version has been moved up. Adding this lockdep coverage unearthed a handful of seqcount bugs which have been addressed already independent of this. While generally useful this comes with a Trojan Horse twist: On RT kernels the write side critical section can become preemtible if the writers are serialized by an associated lock, which leads to the well known reader preempts writer livelock. RT prevents this by storing the associated lock pointer independent of lockdep in the seqcount and changing the reader side to block on the lock when a reader detects that a writer is in the write side critical section. - Conversion of seqcount usage sites to associated types and initializers" * tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) locking/seqlock, headers: Untangle the spaghetti monster locking, arch/ia64: Reduce header dependencies by moving XTP bits into the new header x86/headers: Remove APIC headers from seqcount: More consistent seqprop names seqcount: Compress SEQCNT_LOCKNAME_ZERO() seqlock: Fold seqcount_LOCKNAME_init() definition seqlock: Fold seqcount_LOCKNAME_t definition seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g hrtimer: Use sequence counter with associated raw spinlock kvm/eventfd: Use sequence counter with associated spinlock userfaultfd: Use sequence counter with associated spinlock NFSv4: Use sequence counter with associated spinlock iocost: Use sequence counter with associated spinlock raid5: Use sequence counter with associated spinlock vfs: Use sequence counter with associated spinlock timekeeping: Use sequence counter with associated raw spinlock xfrm: policy: Use sequence counters with associated lock netfilter: nft_set_rbtree: Use sequence counter with associated rwlock netfilter: conntrack: Use sequence counter with associated spinlock sched: tasks: Use sequence counter with associated spinlock ...

Merge tag 'docs-5.9' of git://git.lwn.net/linux

2020-08-05T05:47:54Z

Pull documentation updates from Jonathan Corbet: "It's been a busy cycle for documentation - hopefully the busiest for a while to come. Changes include: - Some new Chinese translations - Progress on the battle against double words words and non-HTTPS URLs - Some block-mq documentation - More RST conversions from Mauro. At this point, that task is essentially complete, so we shouldn't see this kind of churn again for a while. Unless we decide to switch to asciidoc or something...:) - Lots of typo fixes, warning fixes, and more" * tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits) scripts/kernel-doc: optionally treat warnings as errors docs: ia64: correct typo mailmap: add entry for doc/zh_CN: add cpu-load Chinese version Documentation/admin-guide: tainted-kernels: fix spelling mistake MAINTAINERS: adjust kprobes.rst entry to new location devices.txt: document rfkill allocation PCI: correct flag name docs: filesystems: vfs: correct flag name docs: filesystems: vfs: correct sync_mode flag names docs: path-lookup: markup fixes for emphasis docs: path-lookup: more markup fixes docs: path-lookup: fix HTML entity mojibake CREDITS: Replace HTTP links with HTTPS ones docs: process: Add an example for creating a fixes tag doc/zh_CN: add Chinese translation prefer section doc/zh_CN: add clearing-warn-once Chinese version doc/zh_CN: add admin-guide index doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label futex: MAINTAINERS: Re-add selftests directory ...

Merge tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-03T21:39:35Z

Pull locking updates from Ingo Molnar: - LKMM updates: mostly documentation changes, but also some new litmus tests for atomic ops. - KCSAN updates: the most important change is that GCC 11 now has all fixes in place to support KCSAN, so GCC support can be enabled again. Also more annotations. - futex updates: minor cleanups and simplifications - seqlock updates: merge preparatory changes/cleanups for the 'associated locks' facilities. - lockdep updates: - simplify IRQ trace event handling - add various new debug checks - simplify header dependencies, split out , decouple lockdep from other low level headers some more - fix NMI handling - misc cleanups and smaller fixes * tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) kcsan: Improve IRQ state trace reporting lockdep: Refactor IRQ trace events fields into struct seqlock: lockdep assert non-preemptibility on seqcount_t write lockdep: Add preemption enabled/disabled assertion APIs seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount() seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs seqlock: Reorder seqcount_t and seqlock_t API definitions seqlock: seqcount_t latch: End read sections with read_seqcount_retry() seqlock: Properly format kernel-doc code samples Documentation: locking: Describe seqlock design and usage locking/qspinlock: Do not include atomic.h from qspinlock_types.h locking/atomic: Move ATOMIC_INIT into linux/types.h lockdep: Move list.h inclusion into lockdep.h locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs futex: Remove unused or redundant includes futex: Consistently use fshared as boolean futex: Remove needless goto's futex: Remove put_futex_key() rwsem: fix commas in initialisation docs: locking: Replace HTTP links with HTTPS ones ...

seqlock: Extend seqcount API with associated locks

2020-07-29T14:14:25Z

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

Documentation: locking: Describe seqlock design and usage

2020-07-29T14:14:22Z

Proper documentation for the design and usage of sequence counters and sequential locks does not exist. Complete the seqlock.h documentation as follows: - Divide all documentation on a seqcount_t vs. seqlock_t basis. The description for both mechanisms was intermingled, which is incorrect since the usage constrains for each type are vastly different. - Add an introductory paragraph describing the internal design of, and rationale for, sequence counters. - Document seqcount_t writer non-preemptibility requirement, which was not previously documented anywhere, and provide a clear rationale. - Provide template code for seqcount_t and seqlock_t initialization and reader/writer critical sections. - Recommend using seqlock_t by default. It implicitly handles the serialization and non-preemptibility requirements of writers. At seqlock.h: - Remove references to brlocks as they've long been removed from the kernel. - Remove references to gcc-3.x since the kernel's minimum supported gcc version is 4.9. References: 0f6ed63b1707 ("no need to keep brlock macros anymore...") References: 6ec4476ac825 ("Raise gcc version requirement to 4.9") Signed-off-by: Ahmed S. Darwish Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200720155530.1173732-2-a.darwish@linutronix.de

docs: locking: Replace HTTP links with HTTPS ones

2020-07-16T21:19:51Z

Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200713115728.33905-1-grandmaster@al2klimov.de

Documentation: locking: ww-mutex-design: drop duplicated word

2020-07-13T15:48:31Z

Drop the doubled word "up". Signed-off-by: Randy Dunlap Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Link: https://lore.kernel.org/r/20200703213649.30948-3-rdunlap@infradead.org Signed-off-by: Jonathan Corbet