ALSA: seq: Clear client entry before deleting else at closing

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commit a2ff19f7b7 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.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

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Takashi Iwai 2018-03-09 22:23:31 +01:00 • committed by Ben Hutchings

parent 7880783d9f

commit 3bdc246fac

1 changed files with 2 additions and 2 deletions

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sound/core/seq/seq_clientmgr.c

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