Author: kib
Date: Wed Feb 25 16:17:16 2015
New Revision: 279283
URL: https://svnweb.freebsd.org/changeset/base/279283
Log:
When failing to claim ownership of a umtx_pi, restore the umutex owner
to its previous, unowned state. This avoids compounding an existing
problem of inconsistent ownership.
Submitted by: Eric van Gyzen <eric_van_gy...@dell.com>
Obtained from: Dell Inc.
PR: 198914
MFC after: 1 week
Modified:
head/sys/kern/kern_umtx.c
Modified: head/sys/kern/kern_umtx.c
==============================================================================
--- head/sys/kern/kern_umtx.c Wed Feb 25 16:12:56 2015 (r279282)
+++ head/sys/kern/kern_umtx.c Wed Feb 25 16:17:16 2015 (r279283)
@@ -1741,6 +1741,17 @@ do_lock_pi(struct thread *td, struct umu
error = umtx_pi_claim(pi, td);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
+ if (error != 0) {
+ /*
+ * Since we're going to return an
+ * error, restore the m_owner to its
+ * previous, unowned state to avoid
+ * compounding the problem.
+ */
+ (void)casuword32(&m->m_owner,
+ id | UMUTEX_CONTESTED,
+ UMUTEX_CONTESTED);
+ }
break;
}
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