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ALSA: pcm: Bail out when chmap is already present

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When snd_pcm_add_chmap_ctls() is called to the PCM stream to which a
chmap has been already assigned, it returns as an error due to the
conflicting snd_ctl_add() result.  However, this also clears the
already assigned chmap_kctl field via pcm_chmap_ctl_private_free(),
and becomes inconsistent in the later operation.

This patch adds the check of the conflicting chmap kctl before
actually trying to allocate / assign.  The check failure is treated as
a kernel warning, as the double call of snd_pcm_add_chmap_ctls() is
basically a driver bug and having the stack trace would help
developers to figure out the bad code path.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2016-05-10 16:07:40 +02:00
parent 62f00e40b0
commit 8d879be882
1 changed files with 2 additions and 0 deletions
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2
sound/core/pcm_lib.c
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@ -2595,6 +2595,8 @@ int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
};
int err;
if (WARN_ON(pcm->streams[stream].chmap_kctl))
return -EBUSY;
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;