Date: Tue, 6 Oct 2015 22:28:28 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r288958 - in stable: 10/sys/kern 9/sys/kern Message-ID: <201510062228.t96MSS9a060426@repo.freebsd.org>
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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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