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    Subject[PATCH 3.18 62/68] ALSA: seq: Clear client entry before deleting else at closing
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

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

    From: Takashi Iwai <tiwai@suse.de>

    commit a2ff19f7b70118ced291a28d5313469914de451b upstream.

    When releasing a client, we need to clear the clienttab[] entry at
    first, then call snd_seq_queue_client_leave(). Otherwise, the
    in-flight cell in the queue might be picked up by the timer interrupt
    via snd_seq_check_queue() before calling snd_seq_queue_client_leave(),
    and it's delivered to another queue while the client is clearing
    queues. This may eventually result in an uncleared cell remaining in
    a queue, and the later snd_seq_pool_delete() may need to wait for a
    long time until the event gets really processed.

    By moving the clienttab[] clearance at the beginning of release, any
    event delivery of a cell belonging to this client will fail at a later
    point, since snd_seq_client_ptr() returns NULL. Thus the cell that
    was picked up by the timer interrupt will be returned immediately
    without further delivery, and the long stall of snd_seq_delete_pool()
    can be avoided, too.

    Cc: <stable@vger.kernel.org>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    sound/core/seq/seq_clientmgr.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/sound/core/seq/seq_clientmgr.c
    +++ b/sound/core/seq/seq_clientmgr.c
    @@ -270,12 +270,12 @@ static int seq_free_client1(struct snd_s

    if (!client)
    return 0;
    - snd_seq_delete_all_ports(client);
    - snd_seq_queue_client_leave(client->number);
    spin_lock_irqsave(&clients_lock, flags);
    clienttablock[client->number] = 1;
    clienttab[client->number] = NULL;
    spin_unlock_irqrestore(&clients_lock, flags);
    + snd_seq_delete_all_ports(client);
    + snd_seq_queue_client_leave(client->number);
    snd_use_lock_sync(&client->use_lock);
    snd_seq_queue_client_termination(client->number);
    if (client->pool)

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