[PATCH v3] uwb: properly check kthread_run return value

[Andrey Konovalov]

uwbd_start() calls kthread_run() and checks that the return value is
not NULL. But the return value is not NULL in case kthread_run() fails,
it takes the form of ERR_PTR(-EINTR).

Use IS_ERR() instead.

Also add a check to uwbd_stop().

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---

v2: don't assign error values to rc->uwbd.task.
v1: added a check to uwbd_stop().

---
 drivers/uwb/uwbd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/uwb/uwbd.c b/drivers/uwb/uwbd.c
index 01c20a260a8b..39dd4ef53c77 100644
--- a/drivers/uwb/uwbd.c
+++ b/drivers/uwb/uwbd.c
@@ -302,18 +302,22 @@ static int uwbd(void *param)
 /** Start the UWB daemon */
 void uwbd_start(struct uwb_rc *rc)
 {
-	rc->uwbd.task = kthread_run(uwbd, rc, "uwbd");
-	if (rc->uwbd.task == NULL)
+	struct task_struct *task = kthread_run(uwbd, rc, "uwbd");
+	if (IS_ERR(task)) {
+		rc->uwbd.task = NULL;
 		printk(KERN_ERR "UWB: Cannot start management daemon; "
 		       "UWB won't work\n");
-	else
+	} else {
+		rc->uwbd.task = task;
 		rc->uwbd.pid = rc->uwbd.task->pid;
+	}
 }
 
 /* Stop the UWB daemon and free any unprocessed events */
 void uwbd_stop(struct uwb_rc *rc)
 {
-	kthread_stop(rc->uwbd.task);
+	if (rc->uwbd.task)
+		kthread_stop(rc->uwbd.task);
 	uwbd_flush(rc);
 }
 
-- 
2.14.1.690.gbb1197296e-goog