[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 1/2] xen/rwlocks: call preempt_disable() when taking a rwlock
Similar to spinlocks preemption should be disabled while holding a rwlock. Signed-off-by: Juergen Gross <jgross@xxxxxxxx> --- xen/include/xen/rwlock.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/xen/include/xen/rwlock.h b/xen/include/xen/rwlock.h index 1c221dd0d9..4ee341a182 100644 --- a/xen/include/xen/rwlock.h +++ b/xen/include/xen/rwlock.h @@ -2,6 +2,7 @@ #define __RWLOCK_H__ #include <xen/percpu.h> +#include <xen/preempt.h> #include <xen/smp.h> #include <xen/spinlock.h> @@ -57,10 +58,12 @@ static inline int _read_trylock(rwlock_t *lock) cnts = atomic_read(&lock->cnts); if ( likely(_can_read_lock(cnts)) ) { + preempt_disable(); cnts = (u32)atomic_add_return(_QR_BIAS, &lock->cnts); if ( likely(_can_read_lock(cnts)) ) return 1; atomic_sub(_QR_BIAS, &lock->cnts); + preempt_enable(); } return 0; } @@ -73,6 +76,7 @@ static inline void _read_lock(rwlock_t *lock) { u32 cnts; + preempt_disable(); cnts = atomic_add_return(_QR_BIAS, &lock->cnts); if ( likely(_can_read_lock(cnts)) ) return; @@ -106,6 +110,7 @@ static inline void _read_unlock(rwlock_t *lock) * Atomically decrement the reader count */ atomic_sub(_QR_BIAS, &lock->cnts); + preempt_enable(); } static inline void _read_unlock_irq(rwlock_t *lock) @@ -137,6 +142,7 @@ static inline unsigned int _write_lock_val(void) static inline void _write_lock(rwlock_t *lock) { /* Optimize for the unfair lock case where the fair flag is 0. */ + preempt_disable(); if ( atomic_cmpxchg(&lock->cnts, 0, _write_lock_val()) == 0 ) return; @@ -172,13 +178,21 @@ static inline int _write_trylock(rwlock_t *lock) if ( unlikely(cnts) ) return 0; - return likely(atomic_cmpxchg(&lock->cnts, 0, _write_lock_val()) == 0); + preempt_disable(); + if ( unlikely(atomic_cmpxchg(&lock->cnts, 0, _write_lock_val()) != 0) ) + { + preempt_enable(); + return 0; + } + + return 1; } static inline void _write_unlock(rwlock_t *lock) { ASSERT(_is_write_locked_by_me(atomic_read(&lock->cnts))); atomic_and(~(_QW_CPUMASK | _QW_WMASK), &lock->cnts); + preempt_enable(); } static inline void _write_unlock_irq(rwlock_t *lock) @@ -274,6 +288,7 @@ static inline void _percpu_read_lock(percpu_rwlock_t **per_cpudata, } /* Indicate this cpu is reading. */ + preempt_disable(); this_cpu_ptr(per_cpudata) = percpu_rwlock; smp_mb(); /* Check if a writer is waiting. */ @@ -308,6 +323,7 @@ static inline void _percpu_read_unlock(percpu_rwlock_t **per_cpudata, return; } this_cpu_ptr(per_cpudata) = NULL; + preempt_enable(); smp_wmb(); } -- 2.16.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |