md: md_unregister_thread should cope with being passed NULL

Mostly md_unregister_thread is only called when we know that the
thread is NULL, but sometimes we need to check first.  It is safer
to put the check inside md_unregister_thread itself.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 117ea5f..f30f09c 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5382,6 +5382,8 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
 
 void md_unregister_thread(mdk_thread_t *thread)
 {
+       if (!thread)
+               return;
        dprintk("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
 
        kthread_stop(thread->tsk);

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d019a85..81789fa 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4463,8 +4463,7 @@ static int run(mddev_t *mddev)
 
        return 0;
 abort:
-       if (mddev->thread)
-               md_unregister_thread(mddev->thread);
+       md_unregister_thread(mddev->thread);
        mddev->thread = NULL;
        if (conf) {
                shrink_stripes(conf);