ALSA: xen-front: Reset event channel state on stream clear

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xen_snd_front_evtchnl_pair_clear() resets evt_next_id for both
channels. That is correct for the request channel, where evt_next_id is
used to allocate the next request id. It is wrong for the event channel:
incoming events are validated against evt_id, and evt_id is incremented
by evtchnl_interrupt_evt().

This leaves the expected event id from the previous stream instance. A
backend that restarts event ids for a reopened stream can then have valid
current-position events dropped until the stale frontend id catches up.

Reset evt_id for the event channel. Also advance the event-page consumer
to the current producer while clearing the stream, so obsolete events
queued for the previous stream instance are not delivered to the next
ALSA runtime.

Fixes: 1cee559351 ("ALSA: xen-front: Implement ALSA virtual sound driver")
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260526-alsa-xen-event-channel-fixes-v1-1-91d3a6a50778@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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Cássio Gabriel 2026-05-26 09:48:26 -03:00 • committed by Takashi Iwai

parent a238120042

commit 9cd8115237

2 changed files with 8 additions and 4 deletions

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8

sound/xen/xen_snd_front_evtchnl.c

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4

sound/xen/xen_snd_front_evtchnl.h

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