[tip: locking/core] locking/rwsem: Add context analysis
From: tip-bot2 for Peter Zijlstra
Date: Mon Mar 09 2026 - 15:51:12 EST
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 739690915ce1f017223ef4e6f3cc966ccfa3c861
Gitweb: https://git.kernel.org/tip/739690915ce1f017223ef4e6f3cc966ccfa3c861
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 06 Mar 2026 10:43:56 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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) <peterz@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260306101417.GT1282955@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
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 != NULL;
+ return data_race(sem->first_waiter != NULL);
}
#if defined(CONFIG_DEBUG_RWSEMS) || defined(CONFIG_DETECT_HUNG_TASK_BLOCKER)
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 := n
CONTEXT_ANALYSIS_mutex.o := y
CONTEXT_ANALYSIS_rtmutex_api.o := y
CONTEXT_ANALYSIS_ww_rt_mutex.o := y
+CONTEXT_ANALYSIS_rwsem.o := y
obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
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 rwbase_rt *rwb,
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 = &rwb->rtmutex;
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 = sem;
#endif
atomic_long_set(&sem->count, RWSEM_UNLOCKED_VALUE);
- raw_spin_lock_init(&sem->wait_lock);
- sem->first_waiter = NULL;
atomic_long_set(&sem->owner, 0L);
+ scoped_guard (raw_spinlock_init, &sem->wait_lock) {
+ sem->first_waiter = NULL;
+ }
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
osq_lock_init(&sem->osq);
#endif
@@ -365,6 +366,7 @@ enum rwsem_wake_type {
static inline
bool __rwsem_del_waiter(struct rw_semaphore *sem, struct rwsem_waiter *waiter)
+ __must_hold(&sem->wait_lock)
{
if (list_empty(&waiter->list)) {
sem->first_waiter = 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 = 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 = sem->first_waiter;
long count, new;
@@ -1558,6 +1562,7 @@ static inline bool is_rwsem_reader_owned(struct rw_semaphore *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);
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_semaphore *sem)
EXPORT_SYMBOL(down_read_interruptible);
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 = __down_read_trylock(sem);
@@ -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 = __down_write_trylock(sem);
@@ -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
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 subclass)
EXPORT_SYMBOL(down_read_nested);
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 *sem, int subclass)
EXPORT_SYMBOL(down_read_killable_nested);
void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
+ __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);
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);
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);
int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass)
+ __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_semaphore *sem, int subclass)
EXPORT_SYMBOL(down_write_killable_nested);
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);