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Differential D54102

snd_uaudio: Do not use pcm_channel->lock to protect uaudio_chan
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Authored by christos on Sat, Dec 6, 2:52 PM.

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Reviewers
markj
emaste
Summary

This is a layering violation, but it also makes the control flow
confusing; snd_uaudio(4) should have its own lock to protect its
structures.

Fixes: 5cc34a83e1 ("Revert "sound: Merge chn_intr() with chn_intr_locked()"")
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Diff Detail

Repository
rG FreeBSD src repository
Lint
Lint Skipped
Unit
Tests Skipped
Build Status
Buildable 69100
Build 65983: arc lint + arc unit

Event Timeline

christos created this revision.Sat, Dec 6, 2:52 PM
Herald added a subscriber: imp. · View Herald TranscriptSat, Dec 6, 2:52 PM
christos requested review of this revision.Sat, Dec 6, 2:52 PM
Harbormaster completed remote builds in B69100: Diff 167647.Sat, Dec 6, 2:52 PM
markj added a comment.Mon, Dec 8, 2:50 PM

What problem does this fix?

christos added a comment.Mon, Dec 8, 2:52 PM
In D54102#1236568, @markj wrote:

What problem does this fix?

From the commit referenced in "Fixes" (5cc34a83e1):

It turns out that snd_uaudio(4) uses sound(4)'s channel lock for its USB
transfer callbacks. I will try to address this at some point, because
this is layering violation, but for now we need to revert the commit, as
it causes a lock recursion panic with USB audio devices.

Revision Contents
Changeset List

PathSize
sys/
dev/
sound/
usb/
27 lines

Diff 167647

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sys/dev/sound/usb/uaudio.c

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