mm: userfaultfd: Use swap() in double_pt_lock()

[PATCH] mm: userfaultfd: Use swap() in double_pt_lock()

Posted by Jiapeng Chong 1 year, 8 months ago

Use existing swap() function rather than duplicating its implementation.

./mm/userfaultfd.c:1006:13-14: WARNING opportunity for swap()

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9266
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
---
 mm/userfaultfd.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index defa5109cc62..5e7f2801698a 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -995,14 +995,8 @@ void double_pt_lock(spinlock_t *ptl1,
 	__acquires(ptl1)
 	__acquires(ptl2)
 {
-	spinlock_t *ptl_tmp;
-
-	if (ptl1 > ptl2) {
-		/* exchange ptl1 and ptl2 */
-		ptl_tmp = ptl1;
-		ptl1 = ptl2;
-		ptl2 = ptl_tmp;
-	}
+	if (ptl1 > ptl2)
+		swap(ptl1, ptl2);
 	/* lock in virtual address order to avoid lock inversion */
 	spin_lock(ptl1);
 	if (ptl1 != ptl2)
-- 
2.20.1.7.g153144c

Re: [PATCH] mm: userfaultfd: Use swap() in double_pt_lock()

Posted by Wei Yang 1 year, 8 months ago

On Fri, May 31, 2024 at 05:16:43PM +0800, Jiapeng Chong wrote:
>Use existing swap() function rather than duplicating its implementation.
>
>/mm/userfaultfd.c:1006:13-14: WARNING opportunity for swap()
>
>Reported-by: Abaci Robot <abaci@linux.alibaba.com>
>Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9266
>Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>

Reviewed-by: Wei Yang <richard.weiyang@gmail.com>

-- 
Wei Yang
Help you, Help me

Re: [PATCH] mm: userfaultfd: Use swap() in double_pt_lock()

Posted by David Hildenbrand 1 year, 8 months ago

On 31.05.24 11:16, Jiapeng Chong wrote:
> Use existing swap() function rather than duplicating its implementation.
> 
> ./mm/userfaultfd.c:1006:13-14: WARNING opportunity for swap()
> 
> Reported-by: Abaci Robot <abaci@linux.alibaba.com>
> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9266
> Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
> ---
>   mm/userfaultfd.c | 10 ++--------
>   1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index defa5109cc62..5e7f2801698a 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -995,14 +995,8 @@ void double_pt_lock(spinlock_t *ptl1,
>   	__acquires(ptl1)
>   	__acquires(ptl2)
>   {
> -	spinlock_t *ptl_tmp;
> -
> -	if (ptl1 > ptl2) {
> -		/* exchange ptl1 and ptl2 */
> -		ptl_tmp = ptl1;
> -		ptl1 = ptl2;
> -		ptl2 = ptl_tmp;
> -	}
> +	if (ptl1 > ptl2)
> +		swap(ptl1, ptl2);
>   	/* lock in virtual address order to avoid lock inversion */
>   	spin_lock(ptl1);
>   	if (ptl1 != ptl2)

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb