ALSA: pcm: One more dependency for hw constraints

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>

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 2336bf9243e185cd0e8b84b4afe3add26faf59b6..2e1200d17d0cbe5e8a5ef23ffbe1b7f4e17a94f2 100644 (file)
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -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;

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 9f3f8e953ff04ef7eb49b0928d1a09b918177c03..c4aac703dc224c0c58995239275fe2c515be445c 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -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.
                 *