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

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Date:	Wed, 04 Sep 2013 23:12:26 -0700
From:	Joe Perches <joe@...ches.com>
To:	Duan Jiong <duanj.fnst@...fujitsu.com>
Cc:	perex@...ex.cz, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: emu10k1: casting (void *) value returned by
 kcalloc is useless

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;



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