X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=drivers%2Fmd%2Fmd.c;h=5c95ccb595007cab1aba9859cc4da62cad80536f;hp=5404b229582021c9c3811934ea73c6fa4efa1eca;hb=62ddc0046eae6b8e8374f0ac3b27b12a57baa2f6;hpb=87adf1c66cacbc4acd0e696c896755a5091a9d3d

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 5404b2295820..5c95ccb59500 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -61,6 +61,11 @@
 static void autostart_arrays(int part);
 #endif
 
+/* pers_list is a list of registered personalities protected
+ * by pers_lock.
+ * pers_lock does extra service to protect accesses to
+ * mddev->thread when the mutex cannot be held.
+ */
 static LIST_HEAD(pers_list);
 static DEFINE_SPINLOCK(pers_lock);
 
@@ -739,7 +744,12 @@ static void mddev_unlock(mddev_t * mddev)
 	} else
 		mutex_unlock(&mddev->reconfig_mutex);
 
+	/* was we've dropped the mutex we need a spinlock to
+	 * make sur the thread doesn't disappear
+	 */
+	spin_lock(&pers_lock);
 	md_wakeup_thread(mddev->thread);
+	spin_unlock(&pers_lock);
 }
 
 static mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
@@ -6429,11 +6439,18 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
 	return thread;
 }
 
-void md_unregister_thread(mdk_thread_t *thread)
+void md_unregister_thread(mdk_thread_t **threadp)
 {
+	mdk_thread_t *thread = *threadp;
 	if (!thread)
 		return;
 	dprintk("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
+	/* Locking ensures that mddev_unlock does not wake_up a
+	 * non-existent thread
+	 */
+	spin_lock(&pers_lock);
+	*threadp = NULL;
+	spin_unlock(&pers_lock);
 
 	kthread_stop(thread->tsk);
 	kfree(thread);
@@ -7340,8 +7357,7 @@ static void reap_sync_thread(mddev_t *mddev)
 	mdk_rdev_t *rdev;
 
 	/* resync has finished, collect result */
-	md_unregister_thread(mddev->sync_thread);
-	mddev->sync_thread = NULL;
+	md_unregister_thread(&mddev->sync_thread);
 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
 	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
 		/* success...*/