>Number: 171838
>Category: misc
>Synopsis: Possible lock reversal and duplicate locks as reported by
>Witness
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Sep 21 06:50:07 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Venkat Duvvuru
>Release: 9.0-RELEASE
>Organization:
Emulex
>Environment:
FreeBSD root@xxx FreeBsd 9.0-RELEASE FreeBSD 9.0-RELEASE #12: Thu Aug 23
23:42:39 IST 2012 root@root@xxx FreeBsd:/usr/obj/usr/src/sys/GENERIC amd64
>Description:
This patch is for Freebsd nic "oce" driver
(http://svn.freebsd.org/base/head/sys/dev/oce/)
I am attaching a patch which fixes some issues which were reported by witness.
Specifically,
- Calling mtx_init with same name causes WITNESS to report possible lock
reversal and duplicate lock issues.
- release mtx_lock before invoking taskqueue_drain.
>How-To-Repeat:
>Fix:
Fix is attached in the form of patch.
Patch attached with submission follows:
Index: oce_if.c
===================================================================
--- oce_if.c (revision 233768)
+++ oce_if.c (working copy)
@@ -1816,6 +1816,9 @@
}
+/* NOTE : This should only be called holding
+ * DEVICE_LOCK.
+*/
static void
oce_if_deactivate(POCE_SOFTC sc)
{
@@ -1845,11 +1848,17 @@
/* Stop intrs and finish any bottom halves pending */
oce_hw_intr_disable(sc);
+ /* Since taskqueue_drain takes a Gaint Lock, We should not acquire
+ any other lock. So unlock device lock and require after
+ completing taskqueue_drain.
+ */
+ UNLOCK(&sc->dev_lock);
for (i = 0; i < sc->intr_count; i++) {
if (sc->intrs[i].tq != NULL) {
taskqueue_drain(sc->intrs[i].tq, &sc->intrs[i].task);
}
}
+ LOCK(&sc->dev_lock);
/* Delete RX queue in card with flush param */
oce_stop_rx(sc);
Index: oce_if.h
===================================================================
--- oce_if.h (revision 233768)
+++ oce_if.h (working copy)
@@ -493,7 +493,7 @@
#define LOCK_CREATE(lock, desc) { \
strncpy((lock)->name, (desc), MAX_LOCK_DESC_LEN); \
(lock)->name[MAX_LOCK_DESC_LEN] = '\0'; \
- mtx_init(&(lock)->mutex, (lock)->name, MTX_NETWORK_LOCK, MTX_DEF); \
+ mtx_init(&(lock)->mutex, (lock)->name, NULL, MTX_DEF); \
}
#define LOCK_DESTROY(lock) \
if (mtx_initialized(&(lock)->mutex))\
>Release-Note:
>Audit-Trail:
>Unformatted:
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