linux-kernel - [PATCH 3.16 08/16] HID: debug: fix error handling in hid_debug_events

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Message-ID: <lsq.1553232018.587002036@decadent.org.uk>
Date:   Fri, 22 Mar 2019 05:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Jiri Kosina" <jkosina@...e.cz>, "Jiri Slaby" <jslaby@...e.cz>
Subject: [PATCH 3.16 08/16] HID: debug: fix error handling in
 hid_debug_events_read()

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

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

From: Jiri Kosina <jkosina@...e.cz>

commit 8fec02a73e31407e14986fca67dab48d4f777f0e upstream.

In the unlikely case of hdev vanishing while hid_debug_events_read() was
sleeping, we can't really break out of the case switch as with other cases,
as on the way out we'll try to remove ourselves from the hdev waitqueue.

Fix this by taking a shortcut exit path and avoiding cleanup that doesn't
make sense in case hdev doesn't exist any more anyway.

Reported-by: Jiri Slaby <jslaby@...e.cz>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hid/hid-debug.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -1127,7 +1127,8 @@ static ssize_t hid_debug_events_read(str
 
 				if (!list->hdev || !list->hdev->debug) {
 					ret = -EIO;
-					break;
+					set_current_state(TASK_RUNNING);
+					goto out;
 				}
 
 				/* allow O_NONBLOCK from other threads */