linux-kernel - Re: [PATCH] ALSA: emu10k1: casting (void *) value returned by kcalloc is useless

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Date:	Thu, 05 Sep 2013 18:10:36 +0800
From:	Duan Jiong <duanj.fnst@...fujitsu.com>
To:	Joe Perches <joe@...ches.com>
CC:	perex@...ex.cz, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: emu10k1: casting (void *) value returned by kcalloc
 is useless

于 2013年09月05日 14:12, Joe Perches 写道:
> On Thu, 2013-09-05 at 13:57 +0800, Duan Jiong wrote:
>> From: Duan Jiong <duanj.fnst@...fujitsu.com>
>>
>> Casting (void *) value returned by kcalloc is useless
>> as mentioned in Documentation/CodingStyle, Chap 14.
> 
> __user is an important marker that is lost here.
> 
>> diff --git a/sound/pci/emu10k1/emufx.c b/sound/pci/emu10k1/emufx.c
> []
>> @@ -1183,9 +1183,8 @@ static int _snd_emu10k1_audigy_init_efx(struct snd_emu10k1 *emu)
>>  	mm_segment_t seg;
>>  
>>  	if ((icode = kzalloc(sizeof(*icode), GFP_KERNEL)) == NULL ||
>> -	    (icode->gpr_map = (u_int32_t __user *)
>> -	     kcalloc(512 + 256 + 256 + 2 * 1024, sizeof(u_int32_t),
>> -		     GFP_KERNEL)) == NULL ||
>> +	    (icode->gpr_map = kcalloc(512 + 256 + 256 + 2 * 1024,
>> +				sizeof(u_int32_t), GFP_KERNEL)) == NULL ||
>>  	    (controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
>>  				sizeof(*controls), GFP_KERNEL)) == NULL) {
>>  		err = -ENOMEM;
> 
> I think this would be clearer as
> 
> 	err = -ENOMEM;
> 	icode = kzalloc(sizeof(*icode), GFP_KERNEL)
> 	if (!icode)
> 		goto err;
> 	icode->gpr_map = (__user)kcalloc(512 + 256 + 256 + 2 * 1024,
> 					 sizeof(u_int32_t), GFP_KERNEL);
> 	if (!icode->gpr_map)
> 		goto err;
> 	controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
> 			    sizeof(*controls), GFP_KERNEL);
> 	if (!controls)
> 		goto err;
> 

Maybe it should keep the original style, because i do as you said, and
error messages appear during compiling the kernel.

Thanks,
  Duan

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