linux.git/include/linux/rwlock.h, branch v7.1-rc3

locking: Add lock context support in do_raw_{read,write}_trylock()

2026-03-16T12:16:50+00:00

Convert do_raw_{read,write}_trylock() from macros into inline functions
and annotate these inline functions with __cond_acquires_shared() or
__cond_acquires() as appropriate. This change is necessary to build
kernel drivers or subsystems that use rwlock synchronization objects with
lock context analysis enabled. The return type 'int' matches the return
type for CONFIG_DEBUG_SPINLOCK=y.

Signed-off-by: Bart Van Assche 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/20260313171510.230998-3-bvanassche@acm.org

locking: Fix rwlock and spinlock lock context annotations

2026-02-27T15:40:19+00:00

Fix two incorrect rwlock_t lock context annotations. Add the raw_spinlock_t
lock context annotations that are missing.

Fixes: f16a802d402d ("locking/rwlock, spinlock: Support Clang's context analysis")
Signed-off-by: Bart Van Assche 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Marco Elver 
Link: https://patch.msgid.link/20260225183244.4035378-2-bvanassche@acm.org

compiler-context-analysis: Remove __assume_ctx_lock from initializers

2026-01-28T19:45:25+00:00

Remove __assume_ctx_lock() from lock initializers.

Implicitly asserting an active context during initialization caused
false-positive double-lock errors when acquiring a lock immediately after its
initialization. Moving forward, guarded member initialization must either:

	1. Use guard(type_init)(&lock) or scoped_guard(type_init, ...).
	2. Use context_unsafe() for simple initialization.

Reported-by: Bart Van Assche 
Signed-off-by: Marco Elver 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/all/57062131-e79e-42c2-aa0b-8f931cb8cac2@acm.org/
Link: https://patch.msgid.link/20260119094029.1344361-7-elver@google.com

compiler-context-analysis: Remove __cond_lock() function-like helper

2026-01-05T15:43:33+00:00

As discussed in [1], removing __cond_lock() will improve the readability
of trylock code. Now that Sparse context tracking support has been
removed, we can also remove __cond_lock().

Change existing APIs to either drop __cond_lock() completely, or make
use of the __cond_acquires() function attribute instead.

In particular, spinlock and rwlock implementations required switching
over to inline helpers rather than statement-expressions for their
trylock_* variants.

Suggested-by: Peter Zijlstra 
Signed-off-by: Marco Elver 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/all/20250207082832.GU7145@noisy.programming.kicks-ass.net/ [1]
Link: https://patch.msgid.link/20251219154418.3592607-25-elver@google.com

locking/rwlock, spinlock: Support Clang's context analysis

2026-01-05T15:43:28+00:00

Add support for Clang's context analysis for raw_spinlock_t,
spinlock_t, and rwlock. This wholesale conversion is required because
all three of them are interdependent.

To avoid warnings in constructors, the initialization functions mark a
lock as acquired when initialized before guarded variables.

The test verifies that common patterns do not generate false positives.

Signed-off-by: Marco Elver 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://patch.msgid.link/20251219154418.3592607-9-elver@google.com

Improve consistency of '#error' directive messages

2024-11-12T01:17:04+00:00

Remove the use of contractions and use proper punctuation in #error
directive messages that discourage the direct inclusion of header files.

Link: https://lkml.kernel.org/r/20241105032231.28833-1-natanielfarzan@gmail.com
Signed-off-by: Nataniel Farzan 
Signed-off-by: Andrew Morton

locking: Detect includes rwlock.h outside of spinlock.h

2022-09-15T14:14:02+00:00

From: Michael S. Tsirkin 

The check for __LINUX_SPINLOCK_H within rwlock.h (and other files)
detects the direct include of the header file if it is at the very
beginning of the include section.
If it is listed later then chances are high that spinlock.h was already
included (including rwlock.h) and the additional listing of rwlock.h
will not cause any failure.

On PREEMPT_RT this additional rwlock.h will lead to compile failures
since it uses a different rwlock implementation.

Add __LINUX_INSIDE_SPINLOCK_H to spinlock.h and check for this instead
of __LINUX_SPINLOCK_H to detect wrong includes. This will help detect
direct includes of rwlock.h with without PREEMPT_RT enabled.

[ bigeasy: add remaining __LINUX_SPINLOCK_H user and rewrite
  commit description. ]

Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/YweemHxJx7O8rjBx@linutronix.de

locking/rwlocks: introduce write_lock_nested

2022-01-22T06:33:37+00:00

In preparation for converting bit_spin_lock to rwlock in zsmalloc so
that multiple writers of zspages can run at the same time but those
zspages are supposed to be different zspage instance.  Thus, it's not
deadlock.  This patch adds write_lock_nested to support the case for
LOCKDEP.

[minchan@kernel.org: fix write_lock_nested for RT]
  Link: https://lkml.kernel.org/r/YZfrMTAXV56HFWJY@google.com
[bigeasy@linutronix.de: fixup write_lock_nested() implementation]
  Link: https://lkml.kernel.org/r/20211123170134.y6xb7pmpgdn4m3bn@linutronix.de

Link: https://lkml.kernel.org/r/20211115185909.3949505-8-minchan@kernel.org
Signed-off-by: Minchan Kim 
Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Sebastian Andrzej Siewior 
Tested-by: Sebastian Andrzej Siewior 
Cc: Mike Galbraith 
Cc: Sergey Senozhatsky 
Cc: Thomas Gleixner 
Cc: Naresh Kamboju 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

locking: Remove spin_lock_flags() etc

2021-10-30T14:37:28+00:00

parisc, ia64 and powerpc32 are the only remaining architectures that
provide custom arch_{spin,read,write}_lock_flags() functions, which are
meant to re-enable interrupts while waiting for a spinlock.

However, none of these can actually run into this codepath, because
it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
of those combinations are possible on the three architectures.

Going back in the git history, it appears that arch/mn10300 may have
been able to run into this code path, but there is a good chance that
it never worked. On the architectures that still exist, it was
already impossible to hit back in 2008 after the introduction of
CONFIG_GENERIC_LOCKBREAK, and possibly earlier.

As this is all dead code, just remove it and the helper functions built
around it. For arch/ia64, the inline asm could be cleaned up, but
it seems safer to leave it untouched.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Helge Deller   # parisc
Link: https://lore.kernel.org/r/20211022120058.1031690-1-arnd@kernel.org

locking/rwlocks: Add contention detection for rwlocks

2021-02-04T10:27:42+00:00

rwlocks do not currently have any facility to detect contention
like spinlocks do. In order to allow users of rwlocks to better manage
latency, add contention detection for queued rwlocks.

CC: Ingo Molnar 
CC: Will Deacon 
Acked-by: Peter Zijlstra 
Acked-by: Davidlohr Bueso 
Acked-by: Waiman Long 
Acked-by: Paolo Bonzini 
Signed-off-by: Ben Gardon 
Message-Id: <20210202185734.1680553-7-bgardon@google.com>
Signed-off-by: Paolo Bonzini