From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Mon, 15 Oct 2012 20:36:26 +0000 (-0700)
Subject: Condition variable usage, zevent_cv
X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=commitdiff_plain;ds=sidebyside;h=99db9bfde70440475a37c0e1b985efbec4850a8c;p=zfs.git

Condition variable usage, zevent_cv

The following incorrect usage of cv_broadcast() was caught by
code inspection.  The cv_broadcast() function must be called
under the associated mutex to preventing racing with cv_wait().

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
---

diff --git a/module/zfs/fm.c b/module/zfs/fm.c
index ce0ebe0..c004032 100644
--- a/module/zfs/fm.c
+++ b/module/zfs/fm.c
@@ -481,14 +481,13 @@ zfs_zevent_drain_all(int *count)
 static void
 zfs_zevent_insert(zevent_t *ev)
 {
-	mutex_enter(&zevent_lock);
+	ASSERT(MUTEX_HELD(&zevent_lock));
 	list_insert_head(&zevent_list, ev);
+
 	if (zevent_len_cur >= zfs_zevent_len_max)
 		zfs_zevent_drain(list_tail(&zevent_list));
 	else
 		zevent_len_cur++;
-
-	mutex_exit(&zevent_lock);
 }
 
 /*
@@ -528,8 +527,11 @@ zfs_zevent_post(nvlist_t *nvl, nvlist_t *detector, zevent_cb_t *cb)
         ev->ev_nvl = nvl;
 	ev->ev_detector = detector;
 	ev->ev_cb = cb;
+
+	mutex_enter(&zevent_lock);
 	zfs_zevent_insert(ev);
 	cv_broadcast(&zevent_cv);
+	mutex_exit(&zevent_lock);
 }
 
 static int
@@ -1520,9 +1522,10 @@ fm_fini(void)
 	int count;
 
 	zfs_zevent_drain_all(&count);
-	cv_broadcast(&zevent_cv);
 
 	mutex_enter(&zevent_lock);
+	cv_broadcast(&zevent_cv);
+
 	zevent_flags |= ZEVENT_SHUTDOWN;
 	while (zevent_waiters > 0) {
 		mutex_exit(&zevent_lock);