Author: jhb Date: Tue Sep 15 22:16:21 2015 New Revision: 287833 URL: https://svnweb.freebsd.org/changeset/base/287833
Log: 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(). Reported by: mjg Reviewed by: kib, mjg MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D3324 Modified: head/sys/kern/kern_rmlock.c Modified: head/sys/kern/kern_rmlock.c ============================================================================== --- head/sys/kern/kern_rmlock.c Tue Sep 15 21:16:45 2015 (r287832) +++ head/sys/kern/kern_rmlock.c Tue Sep 15 22:16:21 2015 (r287833) @@ -407,9 +407,11 @@ _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); } _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
