user/sven/linux.git/include/linux/cleanup.h, branch v6.13.4

headers/cleanup.h: Remove the if_not_guard() facility

2024-12-07T10:15:14Z

Linus noticed that the new if_not_guard() definition is fragile: "This macro generates actively wrong code if it happens to be inside an if-statement or a loop without a block. IOW, code like this: for (iterate-over-something) if_not_guard(a) return -BUSY; looks like will build fine, but will generate completely incorrect code." The reason is that the __if_not_guard() macro is multi-statement, so while most kernel developers expect macros to be simple or at least compound statements - but for __if_not_guard() it is not so: #define __if_not_guard(_name, _id, args...) \ BUILD_BUG_ON(!__is_cond_ptr(_name)); \ CLASS(_name, _id)(args); \ if (!__guard_ptr(_name)(&_id)) To add insult to injury, the placement of the BUILD_BUG_ON() line makes the macro appear to compile fine, but it will generate incorrect code as Linus reported, for example if used within iteration or conditional statements that will use the first statement of a macro as a loop body or conditional statement body. [ I'd also like to note that the original submission by David Lechner did not contain the BUILD_BUG_ON() line, so it was safer than what we ended up committing. Mea culpa. ] It doesn't appear to be possible to turn this macro into a robust single or compound statement that could be used in single statements, due to the necessity to define an auto scope variable with an open scope and the necessity of it having to expand to a partial 'if' statement with no body. Instead of trying to work around this fragility, just remove the construct before it gets used. Reported-by: Linus Torvalds Signed-off-by: Ingo Molnar Cc: David Lechner Cc: Peter Zijlstra Link: https://lore.kernel.org/r/Z1LBnX9TpZLR5Dkf@gmail.com

Merge tag 'locking-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-11-19T20:43:11Z

Pull locking updates from Ingo Molnar: "Lockdep: - Enable PROVE_RAW_LOCK_NESTING with PROVE_LOCKING (Sebastian Andrzej Siewior) - Add lockdep_cleanup_dead_cpu() (David Woodhouse) futexes: - Use atomic64_inc_return() in get_inode_sequence_number() (Uros Bizjak) - Use atomic64_try_cmpxchg_relaxed() in get_inode_sequence_number() (Uros Bizjak) RT locking: - Add sparse annotation PREEMPT_RT's locking (Sebastian Andrzej Siewior) spinlocks: - Use atomic_try_cmpxchg_release() in osq_unlock() (Uros Bizjak) atomics: - x86: Use ALT_OUTPUT_SP() for __alternative_atomic64() (Uros Bizjak) - x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu() (Uros Bizjak) KCSAN, seqlocks: - Support seqcount_latch_t (Marco Elver) : - Add if_not_guard() conditional guard helper (David Lechner) - Adjust scoped_guard() macros to avoid potential warning (Przemek Kitszel) - Remove address space of returned pointer (Uros Bizjak) WW mutexes: - locking/ww_mutex: Adjust to lockdep nest_lock requirements (Thomas Hellström) Rust integration: - Fix raw_spin_lock initialization on PREEMPT_RT (Eder Zulian) Misc cleanups & fixes: - lockdep: Fix wait-type check related warnings (Ahmed Ehab) - lockdep: Use info level for initial info messages (Jiri Slaby) - spinlocks: Make __raw_* lock ops static (Geert Uytterhoeven) - pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase (Qiuxu Zhuo) - iio: magnetometer: Fix if () scoped_guard() formatting (Stephen Rothwell) - rtmutex: Fix misleading comment (Peter Zijlstra) - percpu-rw-semaphores: Fix grammar in percpu-rw-semaphore.rst (Xiu Jianfeng)" * tag 'locking-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits) locking/Documentation: Fix grammar in percpu-rw-semaphore.rst iio: magnetometer: fix if () scoped_guard() formatting rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT kcsan, seqlock: Fix incorrect assumption in read_seqbegin() seqlock, treewide: Switch to non-raw seqcount_latch interface kcsan, seqlock: Support seqcount_latch_t time/sched_clock: Broaden sched_clock()'s instrumentation coverage time/sched_clock: Swap update_clock_read_data() latch writes locking/atomic/x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu() locking/atomic/x86: Use ALT_OUTPUT_SP() for __alternative_atomic64() cleanup: Add conditional guard helper cleanup: Adjust scoped_guard() macros to avoid potential warning locking/osq_lock: Use atomic_try_cmpxchg_release() in osq_unlock() cleanup: Remove address space of returned pointer locking/rtmutex: Fix misleading comment locking/rt: Annotate unlock followed by lock for sparse. locking/rt: Add sparse annotation for RCU. locking/rt: Remove one __cond_lock() in RT's spin_trylock_irqsave() locking/rt: Add sparse annotation PREEMPT_RT's sleeping locks. locking/pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase ...

deal with the last remaing boolean uses of fd_file()

2024-11-03T06:28:07Z

Reviewed-by: Christian Brauner Signed-off-by: Al Viro

cleanup: Add conditional guard helper

2024-10-25T08:01:51Z

Add a new if_not_guard() macro to cleanup.h for handling conditional guards such as mutext_trylock(). This is more ergonomic than scoped_guard() for most use cases. Instead of hiding the error handling statement in the macro args, it works like a normal if statement and allow the error path to be indented while the normal code flow path is not indented. And it avoid unwanted side-effect from hidden for loop in scoped_guard(). Signed-off-by: David Lechner Co-developed-by: Fabio M. De Francesco Signed-off-by: Fabio M. De Francesco Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dan Williams Link: https://lkml.kernel.org/r/20241001-cleanup-if_not_cond_guard-v1-1-7753810b0f7a@baylibre.com

cleanup: Adjust scoped_guard() macros to avoid potential warning

2024-10-25T08:01:50Z

Change scoped_guard() and scoped_cond_guard() macros to make reasoning about them easier for static analysis tools (smatch, compiler diagnostics), especially to enable them to tell if the given usage of scoped_guard() is with a conditional lock class (interruptible-locks, try-locks) or not (like simple mutex_lock()). Add compile-time error if scoped_cond_guard() is used for non-conditional lock class. Beyond easier tooling and a little shrink reported by bloat-o-meter this patch enables developer to write code like: int foo(struct my_drv *adapter) { scoped_guard(spinlock, &adapter->some_spinlock) return adapter->spinlock_protected_var; } Current scoped_guard() implementation does not support that, due to compiler complaining: error: control reaches end of non-void function [-Werror=return-type] Technical stuff about the change: scoped_guard() macro uses common idiom of using "for" statement to declare a scoped variable. Unfortunately, current logic is too hard for compiler diagnostics to be sure that there is exactly one loop step; fix that. To make any loop so trivial that there is no above warning, it must not depend on any non-const variable to tell if there are more steps. There is no obvious solution for that in C, but one could use the compound statement expression with "goto" jumping past the "loop", effectively leaving only the subscope part of the loop semantics. More impl details: one more level of macro indirection is now needed to avoid duplicating label names; I didn't spot any other place that is using the "for (...; goto label) if (0) label: break;" idiom, so it's not packed for reuse beyond scoped_guard() family, what makes actual macros code cleaner. There was also a need to introduce const true/false variable per lock class, it is used to aid compiler diagnostics reasoning about "exactly 1 step" loops (note that converting that to function would undo the whole benefit). Big thanks to Andy Shevchenko for help on this patch, both internal and public, ranging from whitespace/formatting, through commit message clarifications, general improvements, ending with presenting alternative approaches - all despite not even liking the idea. Big thanks to Dmitry Torokhov for the idea of compile-time check for scoped_cond_guard() (to use it only with conditional locsk), and general improvements for the patch. Big thanks to David Lechner for idea to cover also scoped_cond_guard(). Signed-off-by: Przemek Kitszel Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dmitry Torokhov Link: https://lkml.kernel.org/r/20241018113823.171256-1-przemyslaw.kitszel@intel.com

cleanup: Remove address space of returned pointer

2024-10-25T08:01:50Z

Guard functions in local_lock.h are defined using DEFINE_GUARD() and DEFINE_LOCK_GUARD_1() macros having lock type defined as pointer in the percpu address space. The functions, defined by these macros return value in generic address space, causing: cleanup.h:157:18: error: return from pointer to non-enclosed address space and cleanup.h:214:18: error: return from pointer to non-enclosed address space when strict percpu checks are enabled. Add explicit casts to remove address space of the returned pointer. Found by GCC's named address space checks. Fixes: e4ab322fbaaa ("cleanup: Add conditional guard support") Signed-off-by: Uros Bizjak Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20240819074124.143565-1-ubizjak@gmail.com

Merge tag 'locking-urgent-2024-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-09-29T15:51:30Z

Pull locking updates from Ingo Molnar: "lockdep: - Fix potential deadlock between lockdep and RCU (Zhiguo Niu) - Use str_plural() to address Coccinelle warning (Thorsten Blum) - Add debuggability enhancement (Luis Claudio R. Goncalves) static keys & calls: - Fix static_key_slow_dec() yet again (Peter Zijlstra) - Handle module init failure correctly in static_call_del_module() (Thomas Gleixner) - Replace pointless WARN_ON() in static_call_module_notify() (Thomas Gleixner) : - Add usage and style documentation (Dan Williams) rwsems: - Move is_rwsem_reader_owned() and rwsem_owner() under CONFIG_DEBUG_RWSEMS (Waiman Long) atomic ops, x86: - Redeclare x86_32 arch_atomic64_{add,sub}() as void (Uros Bizjak) - Introduce the read64_nonatomic macro to x86_32 with cx8 (Uros Bizjak)" Signed-off-by: Ingo Molnar * tag 'locking-urgent-2024-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rwsem: Move is_rwsem_reader_owned() and rwsem_owner() under CONFIG_DEBUG_RWSEMS jump_label: Fix static_key_slow_dec() yet again static_call: Replace pointless WARN_ON() in static_call_module_notify() static_call: Handle module init failure correctly in static_call_del_module() locking/lockdep: Simplify character output in seq_line() lockdep: fix deadlock issue between lockdep and rcu lockdep: Use str_plural() to fix Coccinelle warning cleanup: Add usage and style documentation lockdep: suggest the fix for "lockdep bfs error:-1" on print_bfs_bug locking/atomic/x86: Redeclare x86_32 arch_atomic64_{add,sub}() as void locking/atomic/x86: Introduce the read64_nonatomic macro to x86_32 with cx8

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43Z

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

cleanup: Add usage and style documentation

2024-08-05T14:54:41Z

When proposing that PCI grow some new cleanup helpers for pci_dev_put() and pci_dev_{lock,unlock} [1], Bjorn had some fundamental questions about expectations and best practices. Upon reviewing an updated changelog with those details he recommended adding them to documentation in the header file itself. Add that documentation and link it into the rendering for Documentation/core-api/. Signed-off-by: Dan Williams Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Jonathan Cameron Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/171175585714.2192972.12661675876300167762.stgit@dwillia2-xfh.jf.intel.com

Merge tag 'locking-core-2024-07-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-07-16T23:42:37Z

Pull locking updates from Ingo Molnar: - Jump label fixes, including a perf events fix that originally manifested as jump label failures, but was a serialization bug at the usage site - Mark down_write*() helpers as __always_inline, to improve WCHAN debuggability - Misc cleanups and fixes * tag 'locking-core-2024-07-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rwsem: Add __always_inline annotation to __down_write_common() and inlined callers jump_label: Simplify and clarify static_key_fast_inc_cpus_locked() jump_label: Clarify condition in static_key_fast_inc_not_disabled() jump_label: Fix concurrency issues in static_key_slow_dec() perf/x86: Serialize set_attr_rdpmc() cleanup: Standardize the header guard define's name