include/linux/rtmutex.h | 22 +++++++++++++++------- kernel/locking/Makefile | 1 + kernel/locking/rtmutex.c | 5 +++++ kernel/locking/rtmutex_api.c | 6 ++++++ 4 files changed, 27 insertions(+), 7 deletions(-)
The following commit has been merged into the locking/core branch of tip:
Commit-ID: d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2
Gitweb: https://git.kernel.org/tip/d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2
Author: Bart Van Assche <bvanassche@acm.org>
AuthorDate: Tue, 05 May 2026 04:26:44 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 05 May 2026 12:50:49 +02:00
locking/rtmutex: Annotate API and implementation
Add lock context annotations to the rtmutex API and implementation and
enable lock context analysis.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260505022649.870788-1-bvanassche@acm.org
---
include/linux/rtmutex.h | 22 +++++++++++++++-------
kernel/locking/Makefile | 1 +
kernel/locking/rtmutex.c | 5 +++++
kernel/locking/rtmutex_api.c | 6 ++++++
4 files changed, 27 insertions(+), 7 deletions(-)
diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index 78e7e58..9e1f012 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -56,6 +56,8 @@ static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)
#endif
extern void rt_mutex_base_init(struct rt_mutex_base *rtb);
+context_lock_struct(rt_mutex);
+
/**
* The rt_mutex structure
*
@@ -108,8 +110,10 @@ do { \
extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
-extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
-extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock);
+extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
+ __acquires(lock);
+extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
+ __acquires(lock);
#define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
#define rt_mutex_lock_nest_lock(lock, nest_lock) \
do { \
@@ -118,15 +122,19 @@ extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *
} while (0)
#else
-extern void rt_mutex_lock(struct rt_mutex *lock);
+extern void rt_mutex_lock(struct rt_mutex *lock) __acquires(lock);
#define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
#define rt_mutex_lock_nest_lock(lock, nest_lock) rt_mutex_lock(lock)
#endif
-extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
-extern int rt_mutex_lock_killable(struct rt_mutex *lock);
-extern int rt_mutex_trylock(struct rt_mutex *lock);
+extern int rt_mutex_lock_interruptible(struct rt_mutex *lock)
+ __cond_acquires(0, lock);
+extern int rt_mutex_lock_killable(struct rt_mutex *lock)
+ __cond_acquires(0, lock);
+extern int rt_mutex_trylock(struct rt_mutex *lock)
+ __cond_acquires(true, lock);
-extern void rt_mutex_unlock(struct rt_mutex *lock);
+extern void rt_mutex_unlock(struct rt_mutex *lock)
+ __releases(lock);
#endif
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index cee1901..24dc00e 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -4,6 +4,7 @@
KCOV_INSTRUMENT := n
CONTEXT_ANALYSIS_mutex.o := y
+CONTEXT_ANALYSIS_rtmutex.o := y
CONTEXT_ANALYSIS_rtmutex_api.o := y
CONTEXT_ANALYSIS_ww_rt_mutex.o := y
CONTEXT_ANALYSIS_rwsem.o := y
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 4f386ea..69759fd 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -484,6 +484,7 @@ static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_nod
static __always_inline void
rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
+ __must_hold(&lock->wait_lock)
{
lockdep_assert_held(&lock->wait_lock);
@@ -492,6 +493,7 @@ rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
static __always_inline void
rt_mutex_dequeue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter)
+ __must_hold(&lock->wait_lock)
{
lockdep_assert_held(&lock->wait_lock);
@@ -1092,6 +1094,7 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task,
static int __sched
try_to_take_rt_mutex(struct rt_mutex_base *lock, struct task_struct *task,
struct rt_mutex_waiter *waiter)
+ __must_hold(&lock->wait_lock)
{
lockdep_assert_held(&lock->wait_lock);
@@ -1319,6 +1322,7 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
*/
static void __sched mark_wakeup_next_waiter(struct rt_wake_q_head *wqh,
struct rt_mutex_base *lock)
+ __must_hold(&lock->wait_lock)
{
struct rt_mutex_waiter *waiter;
@@ -1479,6 +1483,7 @@ static void __sched rt_mutex_slowunlock(struct rt_mutex_base *lock)
}
static __always_inline void __rt_mutex_unlock(struct rt_mutex_base *lock)
+ __no_context_analysis
{
if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
return;
diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c
index 124219a..23ad997 100644
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -41,6 +41,7 @@ static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock,
unsigned int state,
struct lockdep_map *nest_lock,
unsigned int subclass)
+ __cond_acquires(0, lock)
{
int ret;
@@ -66,12 +67,14 @@ EXPORT_SYMBOL(rt_mutex_base_init);
* @subclass: the lockdep subclass
*/
void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
+ __no_context_analysis /* ignoring the return value below is fine in this case */
{
__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass);
}
EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
+ __no_context_analysis /* ignoring the return value below is fine in this case */
{
__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0);
}
@@ -157,6 +160,7 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock)
{
mutex_release(&lock->dep_map, _RET_IP_);
__rt_mutex_unlock(&lock->rtmutex);
+ __release(lock);
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
@@ -182,6 +186,7 @@ int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock)
*/
bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
struct rt_wake_q_head *wqh)
+ __must_hold(&lock->wait_lock)
{
lockdep_assert_held(&lock->wait_lock);
@@ -312,6 +317,7 @@ int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
struct rt_mutex_waiter *waiter,
struct task_struct *task,
struct wake_q_head *wake_q)
+ __must_hold(&lock->wait_lock)
{
int ret;
On Tue, May 05, 2026 at 10:55:34AM -0000, tip-bot2 for Bart Van Assche wrote:
> The following commit has been merged into the locking/core branch of tip:
>
> Commit-ID: d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2
> Gitweb: https://git.kernel.org/tip/d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2
> Author: Bart Van Assche <bvanassche@acm.org>
> AuthorDate: Tue, 05 May 2026 04:26:44 +02:00
> Committer: Peter Zijlstra <peterz@infradead.org>
> CommitterDate: Tue, 05 May 2026 12:50:49 +02:00
>
> locking/rtmutex: Annotate API and implementation
>
> Add lock context annotations to the rtmutex API and implementation and
> enable lock context analysis.
>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link: https://patch.msgid.link/20260505022649.870788-1-bvanassche@acm.org
This breaks the build for me.
$ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 mrproper defconfig kernel/locking/rtmutex_api.o
kernel/locking/rtmutex_api.c:93:1: error: expecting rt_mutex 'lock' to be held at the end of function [-Werror,-Wthread-safety-analysis]
93 | }
| ^
kernel/locking/rtmutex_api.c:90:14: note: rt_mutex acquired here
90 | void __sched rt_mutex_lock(struct rt_mutex *lock)
| ^
1 error generated.
This is with LLVM 22.1.5, in case it matters.
Cheers,
Nathan
On 5/7/26 10:43 AM, Nathan Chancellor wrote: > On Tue, May 05, 2026 at 10:55:34AM -0000, tip-bot2 for Bart Van Assche wrote: >> The following commit has been merged into the locking/core branch of tip: >> >> Commit-ID: d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2 >> Gitweb: https://git.kernel.org/tip/d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2 >> Author: Bart Van Assche <bvanassche@acm.org> >> AuthorDate: Tue, 05 May 2026 04:26:44 +02:00 >> Committer: Peter Zijlstra <peterz@infradead.org> >> CommitterDate: Tue, 05 May 2026 12:50:49 +02:00 >> >> locking/rtmutex: Annotate API and implementation >> >> Add lock context annotations to the rtmutex API and implementation and >> enable lock context analysis. >> >> Signed-off-by: Bart Van Assche <bvanassche@acm.org> >> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >> Link: https://patch.msgid.link/20260505022649.870788-1-bvanassche@acm.org > > This breaks the build for me. > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 mrproper defconfig kernel/locking/rtmutex_api.o > kernel/locking/rtmutex_api.c:93:1: error: expecting rt_mutex 'lock' to be held at the end of function [-Werror,-Wthread-safety-analysis] > 93 | } > | ^ > kernel/locking/rtmutex_api.c:90:14: note: rt_mutex acquired here > 90 | void __sched rt_mutex_lock(struct rt_mutex *lock) > | ^ > 1 error generated. > > This is with LLVM 22.1.5, in case it matters. Hi Nathan, I think this is the same error as what has been reported by the kernel test robot (https://lore.kernel.org/all/202605060005.JYWpZXr2-lkp@intel.com/). I plan to post a new version with a fix for CONFIG_DEBUG_LOCK_ALLOC=n soon. Thanks, Bart.
On Thu, May 07, 2026 at 12:09:25PM +0200, Bart Van Assche wrote: > On 5/7/26 10:43 AM, Nathan Chancellor wrote: > > On Tue, May 05, 2026 at 10:55:34AM -0000, tip-bot2 for Bart Van Assche wrote: > > > The following commit has been merged into the locking/core branch of tip: > > > > > > Commit-ID: d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2 > > > Gitweb: https://git.kernel.org/tip/d30a456aa7ce1bab05d9b364eeacad0c9cb10cc2 > > > Author: Bart Van Assche <bvanassche@acm.org> > > > AuthorDate: Tue, 05 May 2026 04:26:44 +02:00 > > > Committer: Peter Zijlstra <peterz@infradead.org> > > > CommitterDate: Tue, 05 May 2026 12:50:49 +02:00 > > > > > > locking/rtmutex: Annotate API and implementation > > > > > > Add lock context annotations to the rtmutex API and implementation and > > > enable lock context analysis. > > > > > > Signed-off-by: Bart Van Assche <bvanassche@acm.org> > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > > Link: https://patch.msgid.link/20260505022649.870788-1-bvanassche@acm.org > > > > This breaks the build for me. > > > > $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 mrproper defconfig kernel/locking/rtmutex_api.o > > kernel/locking/rtmutex_api.c:93:1: error: expecting rt_mutex 'lock' to be held at the end of function [-Werror,-Wthread-safety-analysis] > > 93 | } > > | ^ > > kernel/locking/rtmutex_api.c:90:14: note: rt_mutex acquired here > > 90 | void __sched rt_mutex_lock(struct rt_mutex *lock) > > | ^ > > 1 error generated. > > > > This is with LLVM 22.1.5, in case it matters. > > Hi Nathan, > > I think this is the same error as what has been reported by the kernel > test robot > (https://lore.kernel.org/all/202605060005.JYWpZXr2-lkp@intel.com/). > I plan to post a new version with a fix for CONFIG_DEBUG_LOCK_ALLOC=n > soon. Thanks, I missed that report in trying to keep up with my inbox on vacation :) In the meantime, perhaps this should be dropped from locking/core since it is on top? Peter? -- Cheers, Nathan
On Fri, May 08, 2026 at 08:14:56PM +0800, Nathan Chancellor wrote: > Thanks, I missed that report in trying to keep up with my inbox on > vacation :) In the meantime, perhaps this should be dropped from > locking/core since it is on top? Peter? Yes, I was hoping the new version would show up quickly, I'll drop the thing for now.
On 5/8/26 7:57 AM, Peter Zijlstra wrote: > Yes, I was hoping the new version would show up quickly, I'll drop the > thing for now. Please keep in mind that I was attending the LFS/MM/BPF summit this week and hence that I had less time than usual to contribute to the kernel. Bart.
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