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* [PATCH 1/1] mm/zswap: Deletion of an unnecessary check before the function call "free_percpu"
       [not found]                               ` <5317A59D.4@users.sourceforge.net>
@ 2014-11-17 17:40                                 ` SF Markus Elfring
  2014-11-18 22:17                                   ` Seth Jennings
  2016-07-22 18:02                                 ` [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput" SF Markus Elfring
  1 sibling, 1 reply; 5+ messages in thread
From: SF Markus Elfring @ 2014-11-17 17:40 UTC (permalink / raw)
  To: Seth Jennings, linux-mm; +Cc: LKML, kernel-janitors, Coccinelle

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Mon, 17 Nov 2014 18:33:33 +0100

The free_percpu() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 mm/zswap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index ea064c1..35629f0 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -152,8 +152,7 @@ static int __init zswap_comp_init(void)
 static void zswap_comp_exit(void)
 {
 	/* free percpu transforms */
-	if (zswap_comp_pcpu_tfms)
-		free_percpu(zswap_comp_pcpu_tfms);
+	free_percpu(zswap_comp_pcpu_tfms);
 }
 
 /*********************************
-- 
2.1.3

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH 1/1] mm/zswap: Deletion of an unnecessary check before the function call "free_percpu"
  2014-11-17 17:40                                 ` [PATCH 1/1] mm/zswap: Deletion of an unnecessary check before the function call "free_percpu" SF Markus Elfring
@ 2014-11-18 22:17                                   ` Seth Jennings
  0 siblings, 0 replies; 5+ messages in thread
From: Seth Jennings @ 2014-11-18 22:17 UTC (permalink / raw)
  To: SF Markus Elfring; +Cc: linux-mm, LKML, kernel-janitors, Coccinelle

On Mon, Nov 17, 2014 at 06:40:18PM +0100, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Mon, 17 Nov 2014 18:33:33 +0100
> 
> The free_percpu() function tests whether its argument is NULL and then
> returns immediately. Thus the test around the call is not needed.
> 
> This issue was detected by using the Coccinelle software.

Thanks for the cleanup!

Acked-by: Seth Jennings <sjennings@variantweb.net>

> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  mm/zswap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index ea064c1..35629f0 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -152,8 +152,7 @@ static int __init zswap_comp_init(void)
>  static void zswap_comp_exit(void)
>  {
>  	/* free percpu transforms */
> -	if (zswap_comp_pcpu_tfms)
> -		free_percpu(zswap_comp_pcpu_tfms);
> +	free_percpu(zswap_comp_pcpu_tfms);
>  }
>  
>  /*********************************
> -- 
> 2.1.3
> 

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* [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput"
       [not found]                               ` <5317A59D.4@users.sourceforge.net>
  2014-11-17 17:40                                 ` [PATCH 1/1] mm/zswap: Deletion of an unnecessary check before the function call "free_percpu" SF Markus Elfring
@ 2016-07-22 18:02                                 ` SF Markus Elfring
  2016-07-25  0:49                                   ` Sergey Senozhatsky
  2016-07-25  9:08                                   ` Minchan Kim
  1 sibling, 2 replies; 5+ messages in thread
From: SF Markus Elfring @ 2016-07-22 18:02 UTC (permalink / raw)
  To: linux-mm, Minchan Kim, Nitin Gupta, Sergey Senozhatsky
  Cc: LKML, kernel-janitors, Julia Lawall

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 22 Jul 2016 19:54:20 +0200

The iput() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 mm/zsmalloc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 5e5237c..7b5fd2b 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2181,8 +2181,7 @@ static int zs_register_migration(struct zs_pool *pool)
 static void zs_unregister_migration(struct zs_pool *pool)
 {
 	flush_work(&pool->free_work);
-	if (pool->inode)
-		iput(pool->inode);
+	iput(pool->inode);
 }
 
 /*
-- 
2.9.2

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput"
  2016-07-22 18:02                                 ` [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput" SF Markus Elfring
@ 2016-07-25  0:49                                   ` Sergey Senozhatsky
  2016-07-25  9:08                                   ` Minchan Kim
  1 sibling, 0 replies; 5+ messages in thread
From: Sergey Senozhatsky @ 2016-07-25  0:49 UTC (permalink / raw)
  To: SF Markus Elfring
  Cc: linux-mm, Minchan Kim, Nitin Gupta, Sergey Senozhatsky, LKML,
	kernel-janitors, Julia Lawall, Andrew Morton

On (07/22/16 20:02), SF Markus Elfring wrote:
> The iput() function tests whether its argument is NULL and then
> returns immediately. Thus the test around the call is not needed.
> 
> This issue was detected by using the Coccinelle software.

there is no issue; the change is just cosmetic.


> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>



alloc_anon_inode() returns ERR_PTR, so I'd probably rather
change iput() to do IS_ERR_OR_NULL instead of !NULL.

	inode = alloc_anon_inode();
	if (IS_ERR(inode)) {
		inode = NULL;
		^^^^^^^^^^^^^
	}
	...
	iput(inode);

this NULL assignment on error path is a bit fragile.

IOW, something like this

---

diff --git a/fs/inode.c b/fs/inode.c
index 559a9da..f1b7bd2 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1497,7 +1497,7 @@ static void iput_final(struct inode *inode)
  */
 void iput(struct inode *inode)
 {
-       if (!inode)
+       if (IS_ERR_OR_NULL(inode))
                return;
        BUG_ON(inode->i_state & I_CLEAR);
 retry:


---

	-ss

> ---
>  mm/zsmalloc.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 5e5237c..7b5fd2b 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -2181,8 +2181,7 @@ static int zs_register_migration(struct zs_pool *pool)
>  static void zs_unregister_migration(struct zs_pool *pool)
>  {
>  	flush_work(&pool->free_work);
> -	if (pool->inode)
> -		iput(pool->inode);
> +	iput(pool->inode);
>  }
>  
>  /*
> -- 
> 2.9.2
> 

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput"
  2016-07-22 18:02                                 ` [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput" SF Markus Elfring
  2016-07-25  0:49                                   ` Sergey Senozhatsky
@ 2016-07-25  9:08                                   ` Minchan Kim
  1 sibling, 0 replies; 5+ messages in thread
From: Minchan Kim @ 2016-07-25  9:08 UTC (permalink / raw)
  To: SF Markus Elfring
  Cc: linux-mm, Nitin Gupta, Sergey Senozhatsky, LKML, kernel-janitors,
	Julia Lawall

On Fri, Jul 22, 2016 at 08:02:08PM +0200, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Fri, 22 Jul 2016 19:54:20 +0200
> 
> The iput() function tests whether its argument is NULL and then
> returns immediately. Thus the test around the call is not needed.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Minchan Kim <minchan@kernel.org>

Thanks!

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2014-11-17 17:40                                 ` [PATCH 1/1] mm/zswap: Deletion of an unnecessary check before the function call "free_percpu" SF Markus Elfring
2014-11-18 22:17                                   ` Seth Jennings
2016-07-22 18:02                                 ` [PATCH] zsmalloc: Delete an unnecessary check before the function call "iput" SF Markus Elfring
2016-07-25  0:49                                   ` Sergey Senozhatsky
2016-07-25  9:08                                   ` Minchan Kim

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