linux-kernel - [PATCH 3.2 07/94] uwb: properly check kthread

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Message-ID: <lsq.1514480352.914990123@decadent.org.uk>
Date:   Thu, 28 Dec 2017 16:59:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Andrey Konovalov" <andreyknvl@...gle.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.2 07/94] uwb: properly check kthread_run return value

3.2.97-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andrey Konovalov <andreyknvl@...gle.com>

commit bbf26183b7a6236ba602f4d6a2f7cade35bba043 upstream.

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@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/uwb/uwbd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/uwb/uwbd.c
+++ b/drivers/uwb/uwbd.c
@@ -303,18 +303,22 @@ 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);
 }