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    Subject[PATCH 3.13.y-ckt 55/85] Input: evdev - do not report errors form flush()
    Date
    3.13.11-ckt28 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Takashi Iwai <tiwai@suse.de>

    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
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/input/evdev.c | 13 ++++---------
    1 file changed, 4 insertions(+), 9 deletions(-)

    diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
    index c33c8ff..e627bee 100644
    --- a/drivers/input/evdev.c
    +++ b/drivers/input/evdev.c
    @@ -240,19 +240,14 @@ static int evdev_flush(struct file *file, fl_owner_t id)
    {
    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)
    --
    1.9.1


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