Date: Wed, 3 Jul 2002 10:15:26 +0200 (CEST) From: Dan Lukes <dan@obluda.cz> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/40157: early locking in pcm/sound's pcm_chn_add() Message-ID: <200207030815.g638FQKX000383@xkulesh.vol.cz>
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>Number: 40157
>Category: kern
>Synopsis: [PATCH] early locking in pcm/sound's pcm_chn_add()
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Wed Jul 03 11:30:02 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Dan Lukes
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
src/sys/dev/sound/pcm/sound.c,v 1.73 2002/05/19
>Description:
In the code of pcm_chn_add() we obtain a lock and call
sce = malloc(sizeof(*sce), M_DEVBUF, M_WAITOK | M_ZERO)
there is no reason to protect initialising of sce nor calling malloc
by lock on d; malloc is allowed to sleep
we should avoid sleeping with locked things unless necesarry
>How-To-Repeat:
N/A
>Fix:
--- sys/dev/sound/pcm/sound.c.ORIG Sun May 19 08:31:56 2002
+++ sys/dev/sound/pcm/sound.c Wed Jul 3 09:41:36 2002
@@ -428,13 +428,12 @@
struct snddev_channel *sce, *tmp, *after;
int unit = device_get_unit(d->dev);
- snd_mtxlock(d->lock);
-
sce = malloc(sizeof(*sce), M_DEVBUF, M_WAITOK | M_ZERO);
if (!sce) {
- snd_mtxunlock(d->lock);
return ENOMEM;
}
+
+ snd_mtxlock(d->lock);
sce->channel = ch;
if (SLIST_EMPTY(&d->channels)) {
>Release-Note:
>Audit-Trail:
>Unformatted:
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