Author: jhb
Date: Tue Oct 6 22:28:28 2015
New Revision: 288958
URL: https://svnweb.freebsd.org/changeset/base/288958
Log:
MFC 287833:
Threads holding a read lock of a sleepable rm lock are not permitted
to sleep. The rmlock implementation enforces this by disabling
sleeping when a read lock is acquired. To simplify the implementation,
sleeping is disabled for most of the duration of rm_rlock. However,
it doesn't need to be disabled until the lock is acquired. If a
sleepable rm lock is contested, then rm_rlock may need to acquire the
backing sx lock. This tripped the overly-broad assertion. Fix by
relaxing the assertion around the call to sx_xlock().
Modified:
stable/9/sys/kern/kern_rmlock.c
Directory Properties:
stable/9/sys/ (props changed)
Changes in other areas also in this revision:
Modified:
stable/10/sys/kern/kern_rmlock.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/9/sys/kern/kern_rmlock.c
==============================================================================
--- stable/9/sys/kern/kern_rmlock.c Tue Oct 6 21:58:38 2015
(r288957)
+++ stable/9/sys/kern/kern_rmlock.c Tue Oct 6 22:28:28 2015
(r288958)
@@ -375,9 +375,11 @@ _rm_rlock_hard(struct rmlock *rm, struct
return (0);
}
} else {
- if (rm->lock_object.lo_flags & LO_SLEEPABLE)
+ if (rm->lock_object.lo_flags & LO_SLEEPABLE) {
+ THREAD_SLEEPING_OK();
sx_xlock(&rm->rm_lock_sx);
- else
+ THREAD_NO_SLEEPING();
+ } else
mtx_lock(&rm->rm_lock_mtx);
}
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