Date: Sun, 23 Nov 2025 14:50:47 +0100 From: "Christos Margiolis" <christos@freebsd.org> To: "Roman Bogorodskiy" <novel@freebsd.org> Cc: <src-committers@freebsd.org>, <dev-commits-src-all@freebsd.org>, <dev-commits-src-main@freebsd.org> Subject: Re: git: e254ef87a30b - main - sound: Merge chn_intr() with chn_intr_locked() Message-ID: <DEG4FRFOOP7P.G17QPWR74PNL@freebsd.org> In-Reply-To: <aSMNW26jygiaXlox@tulp> References: <69209005.3652b.58fc1f99@gitrepo.freebsd.org> <aSKvtxfqXrFIoXcR@tulp> <DEG3K8ZAO1OX.36AM1L62TO7XJ@freebsd.org> <aSMNW26jygiaXlox@tulp>
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On Sun Nov 23, 2025 at 2:34 PM CET, Roman Bogorodskiy wrote: > Christos Margiolis wrote: > >> On Sun Nov 23, 2025 at 7:54 AM CET, Roman Bogorodskiy wrote: >> > Christos Margiolis wrote: >> > >> >> The branch main has been updated by christos: >> >> >> >> URL: https://cgit.FreeBSD.org/src/commit/?id=e254ef87a30bfcaabc6e4d8e0ecf05f6949a4f06 >> >> >> >> commit e254ef87a30bfcaabc6e4d8e0ecf05f6949a4f06 >> >> Author: Christos Margiolis <christos@FreeBSD.org> >> >> AuthorDate: 2025-11-21 16:14:28 +0000 >> >> Commit: Christos Margiolis <christos@FreeBSD.org> >> >> CommitDate: 2025-11-21 16:14:47 +0000 >> >> >> >> sound: Merge chn_intr() with chn_intr_locked() >> >> >> >> There is no scenario where chn_intr() is called with the channel lock >> >> already held. >> >> >> >> No functional change intended. >> >> >> >> Sponsored by: The FreeBSD Foundation >> >> MFC after: 1 week >> >> Reviewed by: kib, markj >> >> Differential Revision: https://reviews.freebsd.org/D53854 >> >> --- >> >> sys/dev/sound/pcm/channel.c | 20 ++------------------ >> >> sys/dev/sound/pcm/channel.h | 1 - >> >> 2 files changed, 2 insertions(+), 19 deletions(-) >> > >> > With this change my system panics as soon as I start firefox: >> > >> > panic: _mtx_lock_sleep: recursed on non-recursive mutex dsp2.play.0 @ /usr/src/sys/dev/sound/pcm/channel.c:586 >> > >> > Things work fine again with this commit reverted. >> > >> > Roman >> >> Which driver are you using for your sound card? >> >> Christos > > I'm using snd_uaudio(4). If that's important, I have other pcm devices > as well: > > $ cat /dev/sndstat > Installed devices: > pcm0: <Realtek ALC897 (Rear Analog)> (play/rec) > pcm1: <Realtek ALC897 (Analog)> (play/rec) > pcm2: <Generic Philips SPA 20/93> (play/rec) default > No devices installed from userspace. > $ dmesg |grep pcm > pcm2 on uaudio0 > pcm0: <Realtek ALC897 (Rear Analog)> at nid 20 and 24 on hdaa0 > pcm1: <Realtek ALC897 (Analog)> at nid 27 and 26 on hdaa0 > pcm2 on uaudio0 > $ > > Roman Oh, right. I just saw snd_uaudio(4) uses the channel lock (the one your panic says we recursed in), to lock the usb transfer callback, which at some point calls chn_intr(). I actually do not like that snd_uaudio(4) uses sound(4)'s locks to do USB stuff. I just reverted the commit, and will look into solving this afterwards. Christoshelp
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