linux-kernel - Re: [PATCH 1/2] ALSA: ctxfi: Deletion of an unnecessary check before the function call "kfree"

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Date:	Tue, 02 Dec 2014 13:07:44 -0800
From:	Joe Perches <joe@...ches.com>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	alsa-devel@...a-project.org, LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH 1/2] ALSA: ctxfi: Deletion of an unnecessary check
 before the function call "kfree"

On Tue, 2014-12-02 at 21:55 +0100, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 2 Dec 2014 20:00:33 +0100
> 
> The kfree() function performs also input parameter validation.
> Thus the test around the call is not needed.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  sound/pci/ctxfi/ctdaio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/pci/ctxfi/ctdaio.c b/sound/pci/ctxfi/ctdaio.c
> index c1c3f88..1712332 100644
> --- a/sound/pci/ctxfi/ctdaio.c
> +++ b/sound/pci/ctxfi/ctdaio.c
> @@ -577,7 +577,7 @@ static int get_daio_rsc(struct daio_mgr *mgr,
>  error:
>  	if (dao)
>  		kfree(dao);
> -	else if (dai)
> +	else
>  		kfree(dai);
>  
>  	spin_lock_irqsave(&mgr->mgr_lock, flags);

I think this not nice and would prefer something like:

---
 sound/pci/ctxfi/ctdaio.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/sound/pci/ctxfi/ctdaio.c b/sound/pci/ctxfi/ctdaio.c
index c1c3f88..9b87dd2 100644
--- a/sound/pci/ctxfi/ctdaio.c
+++ b/sound/pci/ctxfi/ctdaio.c
@@ -528,8 +528,6 @@ static int get_daio_rsc(struct daio_mgr *mgr,
 			struct daio **rdaio)
 {
 	int err;
-	struct dai *dai = NULL;
-	struct dao *dao = NULL;
 	unsigned long flags;
 
 	*rdaio = NULL;
@@ -544,27 +542,30 @@ static int get_daio_rsc(struct daio_mgr *mgr,
 		return err;
 	}
 
+	err = -ENOMEM;
 	/* Allocate mem for daio resource */
 	if (desc->type <= DAIO_OUT_MAX) {
-		dao = kzalloc(sizeof(*dao), GFP_KERNEL);
-		if (!dao) {
-			err = -ENOMEM;
+		struct dao *dao = kzalloc(sizeof(*dao), GFP_KERNEL);
+		if (!dao)
 			goto error;
-		}
+
 		err = dao_rsc_init(dao, desc, mgr);
-		if (err)
+		if (err) {
+			kfree(dao);
 			goto error;
+		}
 
 		*rdaio = &dao->daio;
 	} else {
-		dai = kzalloc(sizeof(*dai), GFP_KERNEL);
-		if (!dai) {
-			err = -ENOMEM;
+		struct dai *dai = kzalloc(sizeof(*dai), GFP_KERNEL);
+		if (!dai)
 			goto error;
-		}
+
 		err = dai_rsc_init(dai, desc, mgr);
-		if (err)
+		if (err) {
+			kfree(dai);
 			goto error;
+		}
 
 		*rdaio = &dai->daio;
 	}
@@ -575,11 +576,6 @@ static int get_daio_rsc(struct daio_mgr *mgr,
 	return 0;
 
 error:
-	if (dao)
-		kfree(dao);
-	else if (dai)
-		kfree(dai);
-
 	spin_lock_irqsave(&mgr->mgr_lock, flags);
 	daio_mgr_put_rsc(&mgr->mgr, desc->type);
 	spin_unlock_irqrestore(&mgr->mgr_lock, flags);


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