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Use an atomic operation with an appropriate memory barrier when releasing

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a contested sleep mutex in the case that at least two processes are blocked
on the contested mutex.
This commit is contained in:
John Baldwin 2000-11-29 18:41:19 +00:00
parent 8f838cb563
commit f404050e44
3 changed files with 6 additions and 3 deletions
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3
sys/kern/kern_mutex.c
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@ -405,7 +405,8 @@ mtx_exit_hard(struct mtx *m, int type)
_release_lock_quick(m);
CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m);
} else
m->mtx_lock = MTX_CONTESTED;
atomic_store_rel_ptr(&m->mtx_lock,
(void *)MTX_CONTESTED);
pri = MAXPRI;
LIST_FOREACH(m1, &p->p_contested, mtx_contested) {
int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority;

3
sys/kern/subr_turnstile.c
View File

@ -405,7 +405,8 @@ mtx_exit_hard(struct mtx *m, int type)
_release_lock_quick(m);
CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m);
} else
m->mtx_lock = MTX_CONTESTED;
atomic_store_rel_ptr(&m->mtx_lock,
(void *)MTX_CONTESTED);
pri = MAXPRI;
LIST_FOREACH(m1, &p->p_contested, mtx_contested) {
int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority;

3
sys/kern/subr_witness.c
View File

@ -405,7 +405,8 @@ mtx_exit_hard(struct mtx *m, int type)
_release_lock_quick(m);
CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m);
} else
m->mtx_lock = MTX_CONTESTED;
atomic_store_rel_ptr(&m->mtx_lock,
(void *)MTX_CONTESTED);
pri = MAXPRI;
LIST_FOREACH(m1, &p->p_contested, mtx_contested) {
int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority;