[alsa-devel] [PATCH] ASoC: dmaengine: Make the pcm->name equal to pcm->id if the name is not set

[Peter Ujfalusi]

On 10/09/2019 15.07, Takashi Iwai wrote:
> On Fri, 06 Sep 2019 07:55:24 +0200,
> Peter Ujfalusi wrote:
>>
>> Some tools use the snd_pcm_info_get_name() to try to identify PCMs or for
>> other purposes.
>>
>> Currently it is left empty with the dmaengine-pcm, in this case copy the
>> pcm->id string as pcm->name.
>>
>> For example IGT is using this to find the HDMI PCM for testing audio on it.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
>> Reported-by: Arthur She <arthur.she at linaro.org>
>> ---
>> Hi,
>>
>> this was actually reported for 4.14 kernel with omap-pcm (replaced by sdma-pcm
>> in v4.18), since then we only use the generic dmaengine PCM but the same issue
>> applies today.
>>
>> Regards,
>> Peter
>>
>>  sound/soc/soc-generic-dmaengine-pcm.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
>> index 748f5f641002..d93db2c2b527 100644
>> --- a/sound/soc/soc-generic-dmaengine-pcm.c
>> +++ b/sound/soc/soc-generic-dmaengine-pcm.c
>> @@ -306,6 +306,12 @@ static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
>>  
>>  		if (!dmaengine_pcm_can_report_residue(dev, pcm->chan[i]))
>>  			pcm->flags |= SND_DMAENGINE_PCM_FLAG_NO_RESIDUE;
>> +
>> +		if (rtd->pcm->streams[i].pcm->name[0] == '\0') {
>> +			strncpy(rtd->pcm->streams[i].pcm->name,
>> +				rtd->pcm->streams[i].pcm->id,
>> +				sizeof(rtd->pcm->streams[i].pcm->name));
>> +		}
> 
> Any reason to use strncpy() instead of strscpy()?
> After merging Mark's branch, I got a compile warning like:
>   sound/soc/soc-generic-dmaengine-pcm.c:311:4: warning: 'strncpy'
>   accessing 80 bytes at offsets 88 and 24 may overlap up to 0 bytes at
>   offset [9223372036854775807, -9223372036854775808] [-Wrestrict]

I have not seen such a warning.
'may overlap up to 0 bytes' ?
snd_pcm_info {
...
        unsigned char id[64];           /* ID (user selectable) */
        unsigned char name[80];         /* name of this device */
        unsigned char subname[32];      /* subdevice name */
...
};

and strncpy() supposed to be something like this:
char * strncpy(char *dest, const char *src, size_t n)
{
	size_t i;

	for (i = 0; i < n && src[i] != '\0'; i++)
		dest[i] = src[i];
	for ( ; i < n; i++)
		dest[i] = '\0';

	return dest;
}

I can see if I can get my compilers to show the warning and try
strscpy() if it helps on it.

> 
> 
> Takashi
> 
>>  
>>  	return 0;
>> -- 
>> Peter
>>
>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>>
>> _______________________________________________
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>> Alsa-devel at alsa-project.org
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>>

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki