Patch "Input: evdev - do not report errors form flush()" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

Input: evdev - do not report errors form flush()

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
input-evdev-do-not-report-errors-form-flush.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Takashi Iwai <[email protected]>
Date: Thu, 3 Sep 2015 22:20:00 -0700
Subject: Input: evdev - do not report errors form flush()

From: Takashi Iwai <[email protected]>

commit eb38f3a4f6e86f8bb10a3217ebd85ecc5d763aae upstream.

We've got bug reports showing the old systemd-logind (at least system-210) aborting unexpectedly, and this turned out to be because of an invalid error code from close() call to evdev devices. close() is supposed to return only either EINTR or EBADFD, while the device returned ENODEV. logind was overreacting to it and decided to kill itself when an unexpected error code was received. What a tragedy.

The bad error code comes from flush fops, and actually evdev_flush() returns ENODEV when device is disconnected or client's access to it is revoked. But in these cases the fact that flush did not actually happen is not an error, but rather normal behavior. For non-disconnected devices result of flush is also not that interesting as there is no potential of data loss and even if it fails application has no way of handling the error. Because of that we are better off always returning success from evdev_flush().

Also returning EINTR from flush()/close() is discouraged (as it is not clear how application should handle this error), so let's stop taking evdev->mutex interruptibly.

Bugzilla: http://bugzilla.suse.com/show_bug.cgi?id=939834

---
 drivers/input/evdev.c |   13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

@@ -240,19 +240,14 @@ static int evdev_flush(struct file *file
 {
 	struct evdev_client *client = file->private_data;
 	struct evdev *evdev = client->evdev;
-	int retval;
 
-	retval = mutex_lock_interruptible(&evdev->mutex);
-	if (retval)
-		return retval;
+	mutex_lock(&evdev->mutex);
 
-	if (!evdev->exist || client->revoked)
-		retval = -ENODEV;
-	else
-		retval = input_flush_device(&evdev->handle, file);
+	if (evdev->exist && !client->revoked)
+		input_flush_device(&evdev->handle, file);
 
 	mutex_unlock(&evdev->mutex);
-	return retval;
+	return 0;
 }
 
 static void evdev_free(struct device *dev)

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/input-evdev-do-not-report-errors-form-flush.patch queue-3.14/alsa-hda-enable-headphone-jack-detect-on-old-fujitsu-laptops.patch queue-3.14/alsa-hda-use-alc880_fixup_fujitsu-for-fsc-amilo-m1437.patch