Author: mmacy
Date: Mon May 14 00:14:00 2018
New Revision: 333595
URL: https://svnweb.freebsd.org/changeset/base/333595
Log:
epoch(9): allow sx locks to be held across epoch_wait()
The INVARIANTS checks in epoch_wait() were intended to
prevent the block handler from returning with locks held.
What it in fact did was preventing anything except Giant
from being held across it. Check that the number of locks
held has not changed instead.
Approved by: sbruno@
Modified:
head/sys/kern/subr_epoch.c
Modified: head/sys/kern/subr_epoch.c
==============================================================================
--- head/sys/kern/subr_epoch.c Sun May 13 23:56:43 2018 (r333594)
+++ head/sys/kern/subr_epoch.c Mon May 14 00:14:00 2018 (r333595)
@@ -469,7 +469,11 @@ epoch_wait(epoch_t epoch)
int old_cpu;
int old_pinned;
u_char old_prio;
+#ifdef INVARIANTS
+ int locks;
+ locks = curthread->td_locks;
+#endif
INIT_CHECK(epoch);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
@@ -506,9 +510,9 @@ epoch_wait(epoch_t epoch)
/* restore thread priority */
sched_prio(td, old_prio);
thread_unlock(td);
- KASSERT(td->td_locks == 0,
- ("%d locks held", td->td_locks));
PICKUP_GIANT();
+ KASSERT(td->td_locks == locks,
+ ("%d residual locks held", td->td_locks - locks));
}
void
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