Contributions from XFS for FreeBSD project:
- Implement cv_wait_unlock() method which has semantics compatible with the sv_wait() method in IRIX. For cv_wait_unlock(), the lock must be held before entering the function, but is not held when the function is exited. - Implement the existing cv_wait() function in terms of cv_wait_unlock(). Submitted by: kan Feedback from: jhb, trhodes, Christoph Hellwig <hch at infradead dot org>
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parent
6dba929a4e
commit
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=153321
@ -95,17 +95,8 @@ cv_destroy(struct cv *cvp)
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void
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cv_wait(struct cv *cvp, struct mtx *mp)
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{
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struct thread *td;
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WITNESS_SAVE_DECL(mp);
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td = curthread;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold || panicstr) {
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@ -118,6 +109,40 @@ cv_wait(struct cv *cvp, struct mtx *mp)
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return;
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}
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cv_wait_unlock(cvp, mp);
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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}
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/*
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* Wait on a condition variable. This function differs from cv_wait by
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* not aquiring the mutex after condition variable was signaled.
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*/
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void
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cv_wait_unlock(struct cv *cvp, struct mtx *mp)
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{
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struct thread *td;
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td = curthread;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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if (cold || panicstr) {
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/*
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* During autoconfiguration, just give interrupts
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* a chance, then just return. Don't run any other
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* thread or panic below, in case this is the idle
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* process and already asleep.
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*/
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mtx_unlock(mp);
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return;
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}
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sleepq_lock(cvp);
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cvp->cv_waiters++;
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@ -127,13 +152,7 @@ cv_wait(struct cv *cvp, struct mtx *mp)
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sleepq_add(cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
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sleepq_wait(cvp);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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}
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/*
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@ -53,6 +53,7 @@ void cv_init(struct cv *cvp, const char *desc);
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void cv_destroy(struct cv *cvp);
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void cv_wait(struct cv *cvp, struct mtx *mp);
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void cv_wait_unlock(struct cv *cvp, struct mtx *mp);
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int cv_wait_sig(struct cv *cvp, struct mtx *mp);
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int cv_timedwait(struct cv *cvp, struct mtx *mp, int timo);
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int cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo);
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