[PATCH 1/2] ALSA: snd-usb: mixer: propagate errors up the call chain

[PATCH 1/2] ALSA: snd-usb: mixer: propagate errors up the call chain

[Daniel Mack]

In check_input_term() and parse_audio_feature_unit(), propagate the
error value that has been returned by a failing function instead of
-EINVAL. That helps cleaning up the error pathes in the mixer.

Signed-off-by: Daniel Mack <zonque@gmail.com>
---
 sound/usb/mixer.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 638e7f7..db30d02 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -715,8 +715,9 @@ static int check_input_term(struct mixer_build *state, int id, struct usb_audio_
 		case UAC2_CLOCK_SELECTOR: {
 			struct uac_selector_unit_descriptor *d = p1;
 			/* call recursively to retrieve the channel info */
-			if (check_input_term(state, d->baSourceID[0], term) < 0)
-				return -ENODEV;
+			err = check_input_term(state, d->baSourceID[0], term);
+			if (err < 0)
+				return err;
 			term->type = d->bDescriptorSubtype << 16; /* virtual type */
 			term->id = id;
 			term->name = uac_selector_unit_iSelector(d);
@@ -1356,8 +1357,9 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
 		return err;
 
 	/* determine the input source type and name */
-	if (check_input_term(state, hdr->bSourceID, &iterm) < 0)
-		return -EINVAL;
+	err = check_input_term(state, hdr->bSourceID, &iterm);
+	if (err < 0)
+		return err;
 
 	master_bits = snd_usb_combine_bytes(bmaControls, csize);
 	/* master configuration quirks */
-- 
1.8.1.4

[PATCH 2/2] ALSA: snd-usb: mixer: ignore -EINVAL in snd_usb_mixer_controls()

[Daniel Mack]

Creation of individual mixer controls may fail, but that shouldn't cause
the entire mixer creation to fail. Even worse, if the mixer creation
fails, that will error out the entire device probing.

All the functions called by parse_audio_unit() should return -EINVAL if
they find descriptors that are unsupported or believed to be malformed,
so we can safely handle this error code as a non-fatal condition in
snd_usb_mixer_controls().

That fixes a long standing bug which is commonly worked around by
adding quirks which make the driver ignore entire interfaces. Some of
them might now be unnecessary.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-and-tested-by: Rodolfo Thomazelli <pe.soberbo@gmail.com>
---
 sound/usb/mixer.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index db30d02..ac833f0 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2120,7 +2120,7 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 			state.oterm.type = le16_to_cpu(desc->wTerminalType);
 			state.oterm.name = desc->iTerminal;
 			err = parse_audio_unit(&state, desc->bSourceID);
-			if (err < 0)
+			if (err < 0 && err != -EINVAL)
 				return err;
 		} else { /* UAC_VERSION_2 */
 			struct uac2_output_terminal_descriptor *desc = p;
@@ -2132,12 +2132,12 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 			state.oterm.type = le16_to_cpu(desc->wTerminalType);
 			state.oterm.name = desc->iTerminal;
 			err = parse_audio_unit(&state, desc->bSourceID);
-			if (err < 0)
+			if (err < 0 && err != -EINVAL)
 				return err;
 
 			/* for UAC2, use the same approach to also add the clock selectors */
 			err = parse_audio_unit(&state, desc->bCSourceID);
-			if (err < 0)
+			if (err < 0 && err != -EINVAL)
 				return err;
 		}
 	}
-- 
1.8.1.4

Re: [PATCH 1/2] ALSA: snd-usb: mixer: propagate errors up the call chain

[Takashi Iwai]

At Tue, 19 Mar 2013 21:09:24 +0100,
Daniel Mack wrote:
> 
> In check_input_term() and parse_audio_feature_unit(), propagate the
> error value that has been returned by a failing function instead of
> -EINVAL. That helps cleaning up the error pathes in the mixer.
> 
> Signed-off-by: Daniel Mack <zonque@gmail.com>

Applied both patches now with Cc to stable.
Thanks.


Takashi


> ---
>  sound/usb/mixer.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 638e7f7..db30d02 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -715,8 +715,9 @@ static int check_input_term(struct mixer_build *state, int id, struct usb_audio_
>  		case UAC2_CLOCK_SELECTOR: {
>  			struct uac_selector_unit_descriptor *d = p1;
>  			/* call recursively to retrieve the channel info */
> -			if (check_input_term(state, d->baSourceID[0], term) < 0)
> -				return -ENODEV;
> +			err = check_input_term(state, d->baSourceID[0], term);
> +			if (err < 0)
> +				return err;
>  			term->type = d->bDescriptorSubtype << 16; /* virtual type */
>  			term->id = id;
>  			term->name = uac_selector_unit_iSelector(d);
> @@ -1356,8 +1357,9 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
>  		return err;
>  
>  	/* determine the input source type and name */
> -	if (check_input_term(state, hdr->bSourceID, &iterm) < 0)
> -		return -EINVAL;
> +	err = check_input_term(state, hdr->bSourceID, &iterm);
> +	if (err < 0)
> +		return err;
>  
>  	master_bits = snd_usb_combine_bytes(bmaControls, csize);
>  	/* master configuration quirks */
> -- 
> 1.8.1.4
> 
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