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* [PATCH] ALSA: mips: avoid potential uninitialized variable use
@ 2017-01-16 11:04 Arnd Bergmann
  2017-01-16 12:28   ` Takashi Iwai
  0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2017-01-16 11:04 UTC (permalink / raw)
  To: Jaroslav Kysela, Takashi Iwai
  Cc: linux-mips, Arnd Bergmann, alsa-devel, linux-kernel

MIPS allmodconfig results in this warning:

sound/mips/hal2.c: In function 'hal2_gain_get':
sound/mips/hal2.c:224:35: error: 'r' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c:223:35: error: 'l' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c: In function 'hal2_gain_put':
sound/mips/hal2.c:260:13: error: 'new' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/mips/hal2.c:260:13: error: 'old' may be used uninitialized in this function [-Werror=maybe-uninitialized]

It's easy enough to avoid by adding a 'default' clause to the switch
statements here. I assume that in practice no other case can happen,
but adding a default puts us on the safe side and shuts up the warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 sound/mips/hal2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sound/mips/hal2.c b/sound/mips/hal2.c
index ede449f0b50d..0af4f7a9b3e7 100644
--- a/sound/mips/hal2.c
+++ b/sound/mips/hal2.c
@@ -219,6 +219,9 @@ static int hal2_gain_get(struct snd_kcontrol *kcontrol,
 		l = (tmp >> H2I_C2_L_GAIN_SHIFT) & 15;
 		r = (tmp >> H2I_C2_R_GAIN_SHIFT) & 15;
 		break;
+	default:
+		l = 0;
+		r = 0;
 	}
 	ucontrol->value.integer.value[0] = l;
 	ucontrol->value.integer.value[1] = r;
@@ -256,6 +259,9 @@ static int hal2_gain_put(struct snd_kcontrol *kcontrol,
 		new |= (r << H2I_C2_R_GAIN_SHIFT);
 		hal2_i_write32(hal2, H2I_ADC_C2, new);
 		break;
+	default:
+		new = 0;
+		old = 0;
 	}
 	return old != new;
 }
-- 
2.9.0

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] ALSA: mips: avoid potential uninitialized variable use
@ 2017-01-16 12:28   ` Takashi Iwai
  0 siblings, 0 replies; 4+ messages in thread
From: Takashi Iwai @ 2017-01-16 12:28 UTC (permalink / raw)
  To: Arnd Bergmann; +Cc: Jaroslav Kysela, alsa-devel, linux-mips, linux-kernel

On Mon, 16 Jan 2017 12:04:56 +0100,
Arnd Bergmann wrote:
> 
> MIPS allmodconfig results in this warning:
> 
> sound/mips/hal2.c: In function 'hal2_gain_get':
> sound/mips/hal2.c:224:35: error: 'r' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c:223:35: error: 'l' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c: In function 'hal2_gain_put':
> sound/mips/hal2.c:260:13: error: 'new' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c:260:13: error: 'old' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> It's easy enough to avoid by adding a 'default' clause to the switch
> statements here. I assume that in practice no other case can happen,
> but adding a default puts us on the safe side and shuts up the warnings.

Well, these cases are logical errors that must not happen, so
returning an error would be a "safer", IMO.


thanks,

Takashi

> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  sound/mips/hal2.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/sound/mips/hal2.c b/sound/mips/hal2.c
> index ede449f0b50d..0af4f7a9b3e7 100644
> --- a/sound/mips/hal2.c
> +++ b/sound/mips/hal2.c
> @@ -219,6 +219,9 @@ static int hal2_gain_get(struct snd_kcontrol *kcontrol,
>  		l = (tmp >> H2I_C2_L_GAIN_SHIFT) & 15;
>  		r = (tmp >> H2I_C2_R_GAIN_SHIFT) & 15;
>  		break;
> +	default:
> +		l = 0;
> +		r = 0;
>  	}
>  	ucontrol->value.integer.value[0] = l;
>  	ucontrol->value.integer.value[1] = r;
> @@ -256,6 +259,9 @@ static int hal2_gain_put(struct snd_kcontrol *kcontrol,
>  		new |= (r << H2I_C2_R_GAIN_SHIFT);
>  		hal2_i_write32(hal2, H2I_ADC_C2, new);
>  		break;
> +	default:
> +		new = 0;
> +		old = 0;
>  	}
>  	return old != new;
>  }
> -- 
> 2.9.0
> 
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] ALSA: mips: avoid potential uninitialized variable use
@ 2017-01-16 12:28   ` Takashi Iwai
  0 siblings, 0 replies; 4+ messages in thread
From: Takashi Iwai @ 2017-01-16 12:28 UTC (permalink / raw)
  To: Arnd Bergmann; +Cc: Jaroslav Kysela, alsa-devel, linux-mips, linux-kernel

On Mon, 16 Jan 2017 12:04:56 +0100,
Arnd Bergmann wrote:
> 
> MIPS allmodconfig results in this warning:
> 
> sound/mips/hal2.c: In function 'hal2_gain_get':
> sound/mips/hal2.c:224:35: error: 'r' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c:223:35: error: 'l' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c: In function 'hal2_gain_put':
> sound/mips/hal2.c:260:13: error: 'new' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/mips/hal2.c:260:13: error: 'old' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> It's easy enough to avoid by adding a 'default' clause to the switch
> statements here. I assume that in practice no other case can happen,
> but adding a default puts us on the safe side and shuts up the warnings.

Well, these cases are logical errors that must not happen, so
returning an error would be a "safer", IMO.


thanks,

Takashi

> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  sound/mips/hal2.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/sound/mips/hal2.c b/sound/mips/hal2.c
> index ede449f0b50d..0af4f7a9b3e7 100644
> --- a/sound/mips/hal2.c
> +++ b/sound/mips/hal2.c
> @@ -219,6 +219,9 @@ static int hal2_gain_get(struct snd_kcontrol *kcontrol,
>  		l = (tmp >> H2I_C2_L_GAIN_SHIFT) & 15;
>  		r = (tmp >> H2I_C2_R_GAIN_SHIFT) & 15;
>  		break;
> +	default:
> +		l = 0;
> +		r = 0;
>  	}
>  	ucontrol->value.integer.value[0] = l;
>  	ucontrol->value.integer.value[1] = r;
> @@ -256,6 +259,9 @@ static int hal2_gain_put(struct snd_kcontrol *kcontrol,
>  		new |= (r << H2I_C2_R_GAIN_SHIFT);
>  		hal2_i_write32(hal2, H2I_ADC_C2, new);
>  		break;
> +	default:
> +		new = 0;
> +		old = 0;
>  	}
>  	return old != new;
>  }
> -- 
> 2.9.0
> 
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] ALSA: mips: avoid potential uninitialized variable use
  2017-01-16 12:28   ` Takashi Iwai
  (?)
@ 2017-01-16 13:26   ` Arnd Bergmann
  -1 siblings, 0 replies; 4+ messages in thread
From: Arnd Bergmann @ 2017-01-16 13:26 UTC (permalink / raw)
  To: Takashi Iwai
  Cc: Jaroslav Kysela, alsa-devel, linux-mips, Linux Kernel Mailing List

On Mon, Jan 16, 2017 at 1:28 PM, Takashi Iwai <tiwai@suse.de> wrote:
> On Mon, 16 Jan 2017 12:04:56 +0100,
> Arnd Bergmann wrote:
>> It's easy enough to avoid by adding a 'default' clause to the switch
>> statements here. I assume that in practice no other case can happen,
>> but adding a default puts us on the safe side and shuts up the warnings.
>
> Well, these cases are logical errors that must not happen, so
> returning an error would be a "safer", IMO.

Agreed. I sent out a v2 now.

    Arnd

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-01-16 13:26 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2017-01-16 11:04 [PATCH] ALSA: mips: avoid potential uninitialized variable use Arnd Bergmann
2017-01-16 12:28 ` Takashi Iwai
2017-01-16 12:28   ` Takashi Iwai
2017-01-16 13:26   ` Arnd Bergmann

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