Author: markj Date: Tue Apr 21 17:13:06 2020 New Revision: 360163 URL: https://svnweb.freebsd.org/changeset/base/360163
Log: Handle PCATCH in blockcount_sleep() so it can be interrupted. blockcount_wait() still unconditionally waits for the count to reach zero before returning. Tested by: pho (a larger patch) Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D24513 Modified: head/sys/kern/kern_synch.c head/sys/sys/blockcount.h Modified: head/sys/kern/kern_synch.c ============================================================================== --- head/sys/kern/kern_synch.c Tue Apr 21 17:07:02 2020 (r360162) +++ head/sys/kern/kern_synch.c Tue Apr 21 17:13:06 2020 (r360163) @@ -400,12 +400,12 @@ _blockcount_wakeup(blockcount_t *bc, u_int old) } /* - * Wait for a wakeup. This does not guarantee that the count is still zero on - * return and may be subject to transient wakeups. Callers wanting a precise - * answer should use blockcount_wait() with an interlock. + * Wait for a wakeup or a signal. This does not guarantee that the count is + * still zero on return. Callers wanting a precise answer should use + * blockcount_wait() with an interlock. * - * Return 0 if there is no work to wait for, and 1 if we slept waiting for work - * to complete. In the latter case the counter value must be re-read. + * If there is no work to wait for, return 0. If the sleep was interrupted by a + * signal, return EINTR or ERESTART, and return EAGAIN otherwise. */ int _blockcount_sleep(blockcount_t *bc, struct lock_object *lock, const char *wmesg, @@ -415,10 +415,15 @@ _blockcount_sleep(blockcount_t *bc, struct lock_object uintptr_t lock_state; u_int old; int ret; + bool catch, drop; KASSERT(lock != &Giant.lock_object, ("%s: cannot use Giant as the interlock", __func__)); + catch = (prio & PCATCH) != 0; + drop = (prio & PDROP) != 0; + prio &= PRIMASK; + /* * Synchronize with the fence in blockcount_release(). If we end up * waiting, the sleepqueue lock acquisition will provide the required @@ -428,7 +433,7 @@ _blockcount_sleep(blockcount_t *bc, struct lock_object * ourselves to sleep to avoid jumping ahead. */ if (atomic_load_acq_int(&bc->__count) == 0) { - if (lock != NULL && (prio & PDROP) != 0) + if (lock != NULL && drop) LOCK_CLASS(lock)->lc_unlock(lock); return (0); } @@ -439,23 +444,27 @@ _blockcount_sleep(blockcount_t *bc, struct lock_object if (lock != NULL) lock_state = LOCK_CLASS(lock)->lc_unlock(lock); old = blockcount_read(bc); + ret = 0; do { if (_BLOCKCOUNT_COUNT(old) == 0) { sleepq_release(wchan); - ret = 0; goto out; } if (_BLOCKCOUNT_WAITERS(old)) break; } while (!atomic_fcmpset_int(&bc->__count, &old, old | _BLOCKCOUNT_WAITERS_FLAG)); - sleepq_add(wchan, NULL, wmesg, 0, 0); - sleepq_wait(wchan, prio); - ret = 1; + sleepq_add(wchan, NULL, wmesg, catch ? SLEEPQ_INTERRUPTIBLE : 0, 0); + if (catch) + ret = sleepq_wait_sig(wchan, prio); + else + sleepq_wait(wchan, prio); + if (ret == 0) + ret = EAGAIN; out: PICKUP_GIANT(); - if (lock != NULL && (prio & PDROP) == 0) + if (lock != NULL && !drop) LOCK_CLASS(lock)->lc_lock(lock, lock_state); return (ret); Modified: head/sys/sys/blockcount.h ============================================================================== --- head/sys/sys/blockcount.h Tue Apr 21 17:07:02 2020 (r360162) +++ head/sys/sys/blockcount.h Tue Apr 21 17:13:06 2020 (r360163) @@ -80,9 +80,9 @@ static __inline void _blockcount_wait(blockcount_t *bc, struct lock_object *lo, const char *wmesg, int prio) { - KASSERT((prio & PDROP) == 0, ("%s: invalid prio %x", __func__, prio)); + KASSERT((prio & ~PRIMASK) == 0, ("%s: invalid prio %x", __func__, prio)); - while (_blockcount_sleep(bc, lo, wmesg, prio) != 0) + while (_blockcount_sleep(bc, lo, wmesg, prio) == EAGAIN) ; } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
