[PATCH] mm/ksm: One function call less in __ksm_enter()

[PATCH] mm/ksm: One function call less in __ksm_enter()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 5 Jul 2019 16:02:26 +0200

Avoid an extra function call by using a ternary operator instead of
a conditional statement.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 mm/ksm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 3dc4346411e4..7934bab8ceae 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2521,10 +2521,10 @@ int __ksm_enter(struct mm_struct *mm)
 	 * scanning cursor, otherwise KSM pages in newly forked mms will be
 	 * missed: then we might as well insert at the end of the list.
 	 */
-	if (ksm_run & KSM_RUN_UNMERGE)
-		list_add_tail(&mm_slot->mm_list, &ksm_mm_head.mm_list);
-	else
-		list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list);
+	list_add_tail(&mm_slot->mm_list,
+		      ksm_run & KSM_RUN_UNMERGE
+		      ? &ksm_mm_head.mm_list
+		      : &ksm_scan.mm_slot->mm_list);
 	spin_unlock(&ksm_mmlist_lock);

 	set_bit(MMF_VM_MERGEABLE, &mm->flags);
--
2.22.0

Re: [PATCH] mm/ksm: One function call less in __ksm_enter()

[Kirill Tkhai]

On 05.07.2019 17:16, Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Fri, 5 Jul 2019 16:02:26 +0200
> 
> Avoid an extra function call by using a ternary operator instead of
> a conditional statement.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  mm/ksm.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 3dc4346411e4..7934bab8ceae 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -2521,10 +2521,10 @@ int __ksm_enter(struct mm_struct *mm)
>  	 * scanning cursor, otherwise KSM pages in newly forked mms will be
>  	 * missed: then we might as well insert at the end of the list.
>  	 */
> -	if (ksm_run & KSM_RUN_UNMERGE)
> -		list_add_tail(&mm_slot->mm_list, &ksm_mm_head.mm_list);
> -	else
> -		list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list);
> +	list_add_tail(&mm_slot->mm_list,
> +		      ksm_run & KSM_RUN_UNMERGE
> +		      ? &ksm_mm_head.mm_list
> +		      : &ksm_scan.mm_slot->mm_list);

Despite coccinelle warnings, I'm not sure this patch does not make the readability worse...

>  	spin_unlock(&ksm_mmlist_lock);
> 
>  	set_bit(MMF_VM_MERGEABLE, &mm->flags);