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Differential D47559 Diff 146396 sys/dev/sound/pcm/sound.c

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sys/dev/sound/pcm/sound.c

Show First 20 Lines • Show All 214 Lines • ▼ Show 20 Linespcm_killchans(struct snddev_info *d)
PCM_BUSYASSERT(d); PCM_BUSYASSERT(d);
for (;;) { for (;;) {
again = false; again = false;
/* Make sure all channels are stopped. */ /* Make sure all channels are stopped. */
CHN_FOREACH(ch, d, channels.pcm) { CHN_FOREACH(ch, d, channels.pcm) {
CHN_LOCK(ch); CHN_LOCK(ch);
if ((ch->flags & CHN_F_SLEEPING) == 0 && if (ch->intr_cv.cv_waiters == 0 && CHN_STOPPED(ch) &&
CHN_STOPPED(ch) && ch->inprog == 0) { ch->inprog == 0) {
markjUnsubmitted
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Checking the waiters field directly like this is a bit of a layering violation, though the sound driver framework already does this. In fact, cv_waiters == 0 implies there are no waiters, but the converse is not true: cv_waiters != 0 does not imply that there are waiters.

What happens if the code below is executed and there are no waiters? Is it harmless?

markj: Checking the waiters field directly like this is a bit of a layering violation, though the…
christosAuthorUnsubmitted
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In order to get past this loop we'll have to eventually execute this check without waiters for all channels, so I'm pretty sure it's fine.

christos: In order to get past this loop we'll have to eventually execute this check without waiters for…
christosAuthorUnsubmitted
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Ah sorry, you meant what happens if the lines below this check are executed. Still, nothing. chn_shutdown() calls CHN_BROADCAST() which also checks for cv_waiters, and the rest shouldn't concern the value of cv_waiters anyway.

christos: Ah sorry, you meant what happens if the lines //below// this check are executed. Still, nothing.
CHN_UNLOCK(ch); CHN_UNLOCK(ch);
continue; continue;
} }
chn_shutdown(ch); chn_shutdown(ch);
if (ch->direction == PCMDIR_PLAY) if (ch->direction == PCMDIR_PLAY)
chn_flush(ch); chn_flush(ch);
else else
chn_abort(ch); chn_abort(ch);
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