From nobody Thu Apr 9 09:37:05 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 906F0325495; Mon, 9 Mar 2026 19:48:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773085703; cv=none; b=ShiCp1QmmjMqn5qsoea8nPTszFpCy5Abph8rGaHoboSseO0+JbcwJv/3WA0Hkw04F3wq2nStIakAOn6Umuy7FpSHtMFqxBg3hwszoYCwGp3x8CtqJYc20k5IjPv5angWXIZuAAvXf/8+GNSV2H+4GaaGjEnG8/H7IKfMDt5qqJY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773085703; c=relaxed/simple; bh=xdjPI2GQ8o5sWfhKqaQni2ZkR3e3klhXGor7ylYkVag=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=FpYCaBP5x9uHt/rs8iyhe/rBDpTGna6cl9ZkYhOKnKYvL3IHkofwbb2wcfhjM3BHMtGKfqYQdIT6Bawq6fPZbc4ZZSP9RFrf/JteAQZ29Z1q4dNnbJufIjO7Ulq3McwmIpdnlFh7TwpE6lzhH7COSvr3xt+iBoJsr3AlJL4PaTY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=qVXib2SQ; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=3rp02kSj; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="qVXib2SQ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="3rp02kSj" Date: Mon, 09 Mar 2026 19:48:12 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1773085694; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hzvrE0xCyyig5ytyRoFVDDbebS9yA8pnooqtfZKGdTU=; b=qVXib2SQZapl9KPziVSIanSYhGEpGvkAHK18lKK32Fn41L0q4iaH8scFiOb9XZip4hgRwS /HA4pW79hUWsPTZNGgOKAgP5e9RhlX3eOyIQLWe0ERCwwj2O5FQPuJxxM3mbVWnZURN+GJ bB0xHNAKvuby+mYf4gXngIy2f6WYJf1Z9hRjqhWM0OECUwNLBxlcciwYPJXh5vFQ82JLTh 7THZ3OrfTsrHD+IwIpW/Fu9jQowyvYCaFHUq3Qq7VLGdsVIdQbhuuVexti9QZYj+bYg6RL e+go8P1a6iSbeRwk2eejTY2vXxbonboY9jsX58j8d1oLEapmkCdS9JE8p+QC5w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1773085694; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hzvrE0xCyyig5ytyRoFVDDbebS9yA8pnooqtfZKGdTU=; b=3rp02kSj1HvPpIcStYRcuWaWPYB9X+iNuwc1l39LbrqiDUSyHEr4yCYt7qzObiJHKhX4EF /bbuSw0uEvxjfnCg== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/rwsem: Add context analysis Cc: "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260306101417.GT1282955@noisy.programming.kicks-ass.net> References: <20260306101417.GT1282955@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <177308569284.1647592.15809195949194510946.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the locking/core branch of tip: Commit-ID: 739690915ce1f017223ef4e6f3cc966ccfa3c861 Gitweb: https://git.kernel.org/tip/739690915ce1f017223ef4e6f3cc966cc= fa3c861 Author: Peter Zijlstra AuthorDate: Fri, 06 Mar 2026 10:43:56 +01:00 Committer: Peter Zijlstra CommitterDate: Sun, 08 Mar 2026 11:06:53 +01:00 locking/rwsem: Add context analysis Add compiler context analysis annotations. Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260306101417.GT1282955@noisy.programming.k= icks-ass.net --- include/linux/rwsem.h | 4 ++-- kernel/locking/Makefile | 1 + kernel/locking/rwbase_rt.c | 1 + kernel/locking/rwsem.c | 27 ++++++++++++++++++++++++--- 4 files changed, 28 insertions(+), 5 deletions(-) diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index e782953..6a1a7ba 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -57,7 +57,7 @@ context_lock_struct(rw_semaphore) { struct optimistic_spin_queue osq; /* spinner MCS lock */ #endif raw_spinlock_t wait_lock; - struct rwsem_waiter *first_waiter; + struct rwsem_waiter *first_waiter __guarded_by(&wait_lock); #ifdef CONFIG_DEBUG_RWSEMS void *magic; #endif @@ -131,7 +131,7 @@ do { \ */ static inline bool rwsem_is_contended(struct rw_semaphore *sem) { - return sem->first_waiter !=3D NULL; + return data_race(sem->first_waiter !=3D NULL); } =20 #if defined(CONFIG_DEBUG_RWSEMS) || defined(CONFIG_DETECT_HUNG_TASK_BLOCKE= R) diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile index 0c07de7..cee1901 100644 --- a/kernel/locking/Makefile +++ b/kernel/locking/Makefile @@ -6,6 +6,7 @@ KCOV_INSTRUMENT :=3D n CONTEXT_ANALYSIS_mutex.o :=3D y CONTEXT_ANALYSIS_rtmutex_api.o :=3D y CONTEXT_ANALYSIS_ww_rt_mutex.o :=3D y +CONTEXT_ANALYSIS_rwsem.o :=3D y =20 obj-y +=3D mutex.o semaphore.o rwsem.o percpu-rwsem.o =20 diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c index 9f4322c..82e078c 100644 --- a/kernel/locking/rwbase_rt.c +++ b/kernel/locking/rwbase_rt.c @@ -186,6 +186,7 @@ static __always_inline void rwbase_read_unlock(struct r= wbase_rt *rwb, =20 static inline void __rwbase_write_unlock(struct rwbase_rt *rwb, int bias, unsigned long flags) + __releases(&rwb->rtmutex.wait_lock) { struct rt_mutex_base *rtm =3D &rwb->rtmutex; =20 diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index e66f37e..ba4cb74 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -72,7 +72,7 @@ #c, atomic_long_read(&(sem)->count), \ (unsigned long) sem->magic, \ atomic_long_read(&(sem)->owner), (long)current, \ - (sem)->first_waiter ? "" : "not ")) \ + rwsem_is_contended(sem) ? "" : "not ")) \ debug_locks_off(); \ } while (0) #else @@ -320,9 +320,10 @@ void __init_rwsem(struct rw_semaphore *sem, const char= *name, sem->magic =3D sem; #endif atomic_long_set(&sem->count, RWSEM_UNLOCKED_VALUE); - raw_spin_lock_init(&sem->wait_lock); - sem->first_waiter =3D NULL; atomic_long_set(&sem->owner, 0L); + scoped_guard (raw_spinlock_init, &sem->wait_lock) { + sem->first_waiter =3D NULL; + } #ifdef CONFIG_RWSEM_SPIN_ON_OWNER osq_lock_init(&sem->osq); #endif @@ -365,6 +366,7 @@ enum rwsem_wake_type { =20 static inline bool __rwsem_del_waiter(struct rw_semaphore *sem, struct rwsem_waiter *wai= ter) + __must_hold(&sem->wait_lock) { if (list_empty(&waiter->list)) { sem->first_waiter =3D NULL; @@ -401,6 +403,7 @@ rwsem_del_waiter(struct rw_semaphore *sem, struct rwsem= _waiter *waiter) static inline struct rwsem_waiter *next_waiter(const struct rw_semaphore *sem, const struct rwsem_waiter *waiter) + __must_hold(&sem->wait_lock) { struct rwsem_waiter *next =3D list_first_entry(&waiter->list, struct rwsem_waiter, list); @@ -621,6 +624,7 @@ rwsem_del_wake_waiter(struct rw_semaphore *sem, struct = rwsem_waiter *waiter, */ static inline bool rwsem_try_write_lock(struct rw_semaphore *sem, struct rwsem_waiter *waiter) + __must_hold(&sem->wait_lock) { struct rwsem_waiter *first =3D sem->first_waiter; long count, new; @@ -1558,6 +1562,7 @@ static inline bool is_rwsem_reader_owned(struct rw_se= maphore *sem) * lock for reading */ void __sched down_read(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); @@ -1567,6 +1572,7 @@ void __sched down_read(struct rw_semaphore *sem) EXPORT_SYMBOL(down_read); =20 int __sched down_read_interruptible(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); @@ -1581,6 +1587,7 @@ int __sched down_read_interruptible(struct rw_semapho= re *sem) EXPORT_SYMBOL(down_read_interruptible); =20 int __sched down_read_killable(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); @@ -1598,6 +1605,7 @@ EXPORT_SYMBOL(down_read_killable); * trylock for reading -- returns 1 if successful, 0 if contention */ int down_read_trylock(struct rw_semaphore *sem) + __no_context_analysis { int ret =3D __down_read_trylock(sem); =20 @@ -1611,6 +1619,7 @@ EXPORT_SYMBOL(down_read_trylock); * lock for writing */ void __sched down_write(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); @@ -1622,6 +1631,7 @@ EXPORT_SYMBOL(down_write); * lock for writing */ int __sched down_write_killable(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); @@ -1640,6 +1650,7 @@ EXPORT_SYMBOL(down_write_killable); * trylock for writing -- returns 1 if successful, 0 if contention */ int down_write_trylock(struct rw_semaphore *sem) + __no_context_analysis { int ret =3D __down_write_trylock(sem); =20 @@ -1654,6 +1665,7 @@ EXPORT_SYMBOL(down_write_trylock); * release a read lock */ void up_read(struct rw_semaphore *sem) + __no_context_analysis { rwsem_release(&sem->dep_map, _RET_IP_); __up_read(sem); @@ -1664,6 +1676,7 @@ EXPORT_SYMBOL(up_read); * release a write lock */ void up_write(struct rw_semaphore *sem) + __no_context_analysis { rwsem_release(&sem->dep_map, _RET_IP_); __up_write(sem); @@ -1674,6 +1687,7 @@ EXPORT_SYMBOL(up_write); * downgrade write lock to read lock */ void downgrade_write(struct rw_semaphore *sem) + __no_context_analysis { lock_downgrade(&sem->dep_map, _RET_IP_); __downgrade_write(sem); @@ -1683,6 +1697,7 @@ EXPORT_SYMBOL(downgrade_write); #ifdef CONFIG_DEBUG_LOCK_ALLOC =20 void down_read_nested(struct rw_semaphore *sem, int subclass) + __no_context_analysis { might_sleep(); rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); @@ -1691,6 +1706,7 @@ void down_read_nested(struct rw_semaphore *sem, int s= ubclass) EXPORT_SYMBOL(down_read_nested); =20 int down_read_killable_nested(struct rw_semaphore *sem, int subclass) + __no_context_analysis { might_sleep(); rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); @@ -1705,6 +1721,7 @@ int down_read_killable_nested(struct rw_semaphore *se= m, int subclass) EXPORT_SYMBOL(down_read_killable_nested); =20 void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *n= est) + __no_context_analysis { might_sleep(); rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_); @@ -1713,6 +1730,7 @@ void _down_write_nest_lock(struct rw_semaphore *sem, = struct lockdep_map *nest) EXPORT_SYMBOL(_down_write_nest_lock); =20 void down_read_non_owner(struct rw_semaphore *sem) + __no_context_analysis { might_sleep(); __down_read(sem); @@ -1727,6 +1745,7 @@ void down_read_non_owner(struct rw_semaphore *sem) EXPORT_SYMBOL(down_read_non_owner); =20 void down_write_nested(struct rw_semaphore *sem, int subclass) + __no_context_analysis { might_sleep(); rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); @@ -1735,6 +1754,7 @@ void down_write_nested(struct rw_semaphore *sem, int = subclass) EXPORT_SYMBOL(down_write_nested); =20 int __sched down_write_killable_nested(struct rw_semaphore *sem, int subcl= ass) + __no_context_analysis { might_sleep(); rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); @@ -1750,6 +1770,7 @@ int __sched down_write_killable_nested(struct rw_sema= phore *sem, int subclass) EXPORT_SYMBOL(down_write_killable_nested); =20 void up_read_non_owner(struct rw_semaphore *sem) + __no_context_analysis { DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem); __up_read(sem);