Messages in this thread Patch in this message | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH 1/2] locking: Wire up rwlock_is_contended() on PREEMPT_RT | Date | Mon, 6 Sep 2021 16:30:03 +0200 |
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rwlock_is_contended() should return 0 if there are no waiters pending on that lock on, != 0 otherwise. PREEMPT_RT's implementation of RW-locks provides rt_rwlock_is_contended() which returns != 0 if there is a writer about to acquire the lock. The only downside is that a writter, that is using that function, will always see that this lock is contended even if there are no readers or writters pending.
Wire up rwlock_is_contended() with RT's rt_rwlock_is_contended().
Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- include/linux/rwlock_rt.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/rwlock_rt.h b/include/linux/rwlock_rt.h index 49c1f3842ed5b..e482671ff49ee 100644 --- a/include/linux/rwlock_rt.h +++ b/include/linux/rwlock_rt.h @@ -30,6 +30,7 @@ extern void rt_read_unlock(rwlock_t *rwlock); extern void rt_write_lock(rwlock_t *rwlock); extern int rt_write_trylock(rwlock_t *rwlock); extern void rt_write_unlock(rwlock_t *rwlock); +extern int rt_rwlock_is_contended(rwlock_t *rwlock); static __always_inline void read_lock(rwlock_t *rwlock) { @@ -135,6 +136,6 @@ static __always_inline void write_unlock_irqrestore(rwlock_t *rwlock, rt_write_unlock(rwlock); } -#define rwlock_is_contended(lock) (((void)(lock), 0)) +#define rwlock_is_contended(lock) rt_rwlock_is_contended(lock) #endif /* __LINUX_RWLOCK_RT_H */ -- 2.33.0
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