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Thu, 17 Jul 2025 19:16:54 -0700 (PDT) From: Alexei Starovoitov To: bpf@vger.kernel.org, linux-mm@kvack.org Cc: vbabka@suse.cz, harry.yoo@oracle.com, shakeel.butt@linux.dev, mhocko@suse.com, bigeasy@linutronix.de, andrii@kernel.org, memxor@gmail.com, akpm@linux-foundation.org, peterz@infradead.org, rostedt@goodmis.org, hannes@cmpxchg.org Subject: [PATCH v4 2/6] locking/local_lock: Introduce local_lock_is_locked(). Date: Thu, 17 Jul 2025 19:16:42 -0700 Message-Id: <20250718021646.73353-3-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250718021646.73353-1-alexei.starovoitov@gmail.com> References: <20250718021646.73353-1-alexei.starovoitov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 339D9180004 X-Stat-Signature: ey68fdioyg7384knqqezep9ijntqsntd X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1752805015-727146 X-HE-Meta: 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 ZjiPmtqU 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Alexei Starovoitov Introduce local_lock_is_locked() that returns true when given local_lock is locked by current cpu (in !PREEMPT_RT) or by current task (in PREEMPT_RT). The goal is to detect a deadlock by the caller. Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Alexei Starovoitov --- include/linux/local_lock.h | 2 ++ include/linux/local_lock_internal.h | 7 +++++++ include/linux/rtmutex.h | 10 ++++++++++ kernel/locking/rtmutex_common.h | 9 --------- 4 files changed, 19 insertions(+), 9 deletions(-) diff --git a/include/linux/local_lock.h b/include/linux/local_lock.h index 16a2ee4f8310..092ce89b162a 100644 --- a/include/linux/local_lock.h +++ b/include/linux/local_lock.h @@ -66,6 +66,8 @@ */ #define local_trylock(lock) __local_trylock(lock) +#define local_lock_is_locked(lock) __local_lock_is_locked(lock) + /** * local_trylock_irqsave - Try to acquire a per CPU local lock, save and disable * interrupts if acquired diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h index 85c2e1b1af6b..db61409f040c 100644 --- a/include/linux/local_lock_internal.h +++ b/include/linux/local_lock_internal.h @@ -165,6 +165,9 @@ do { \ !!tl; \ }) +/* preemption or migration must be disabled before calling __local_lock_is_locked */ +#define __local_lock_is_locked(lock) READ_ONCE(this_cpu_ptr(lock)->acquired) + #define __local_lock_release(lock) \ do { \ local_trylock_t *tl; \ @@ -285,4 +288,8 @@ do { \ __local_trylock(lock); \ }) +/* migration must be disabled before calling __local_lock_is_locked */ +#define __local_lock_is_locked(__lock) \ + (rt_mutex_owner(&this_cpu_ptr(__lock)->lock) == current) + #endif /* CONFIG_PREEMPT_RT */ diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h index 7d049883a08a..98391601fe94 100644 --- a/include/linux/rtmutex.h +++ b/include/linux/rtmutex.h @@ -44,6 +44,16 @@ static inline bool rt_mutex_base_is_locked(struct rt_mutex_base *lock) return READ_ONCE(lock->owner) != NULL; } +#ifdef CONFIG_RT_MUTEXES +#define RT_MUTEX_HAS_WAITERS 1UL + +static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) +{ + unsigned long owner = (unsigned long) READ_ONCE(lock->owner); + + return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS); +} +#endif extern void rt_mutex_base_init(struct rt_mutex_base *rtb); /** diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index 78dd3d8c6554..cf6ddd1b23a2 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -153,15 +153,6 @@ static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p) pi_tree.entry); } -#define RT_MUTEX_HAS_WAITERS 1UL - -static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) -{ - unsigned long owner = (unsigned long) READ_ONCE(lock->owner); - - return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS); -} - /* * Constants for rt mutex functions which have a selectable deadlock * detection. -- 2.47.1