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ALSA: pcm: One more dependency for hw constraints

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The fix for a long-standing USB-audio bug required one more dependency
variable to be added to the hw constraints.  Unfortunately I didn't
realize at debugging that the new addition may result in the overflow
of the dependency array of each snd_pcm_hw_rule (up to three plus a
sentinel), because USB-audio driver adds one more dependency only for
a certain device and bus, hence it works as is for many devices.  But
in a bad case, a simple open always results in -EINVAL (with kernel
WARNING if CONFIG_SND_DEBUG is set) no matter what is passed.

Since the dependencies are real and unavoidable (USB-audio restricts
the hw_params per looping over the format/rate/channels combos), the
only good solution seems to raise the bar for one more dependency for
snd_pcm_hw_rule -- so does this patch: now the hw constraint
dependencies can be up to four.

Fixes: 506c203cc3de ("ALSA: usb-audio: Fix hw constraints dependencies")
Reported-by: Jamie Heilman <jamie@audible.transient.net>
Link: https://lore.kernel.org/r/20210123155730.22576-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2021-01-23 16:57:30 +01:00
parent 5de3b94302
commit 23b53d4417
2 changed files with 3 additions and 3 deletions
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2
include/sound/pcm.h
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@ -229,7 +229,7 @@ typedef int (*snd_pcm_hw_rule_func_t)(struct snd_pcm_hw_params *params,
struct snd_pcm_hw_rule {
unsigned int cond;
int var;
int deps[4];
int deps[5];
snd_pcm_hw_rule_func_t func;
void *private;

4
sound/core/pcm_native.c
View File

@ -382,8 +382,8 @@ retry:
continue;
/*
* The 'deps' array includes maximum three dependencies
* to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fourth
* The 'deps' array includes maximum four dependencies
* to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fifth
* member of this array is a sentinel and should be
* negative value.
*