+ mm-userfaultfd-use-swap-in-double_pt_lock.patch added to mm-unstable branch

+ mm-userfaultfd-use-swap-in-double_pt_lock.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: userfaultfd: use swap() in double_pt_lock()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-userfaultfd-use-swap-in-double_pt_lock.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-userfaultfd-use-swap-in-double_pt_lock.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Subject: mm: userfaultfd: use swap() in double_pt_lock()
Date: Fri, 31 May 2024 17:16:43 +0800

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

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

Link: https://lkml.kernel.org/r/20240531091643.67778-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9266
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/userfaultfd.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/mm/userfaultfd.c~mm-userfaultfd-use-swap-in-double_pt_lock
+++ a/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)
_

Patches currently in -mm which might be from jiapeng.chong@linux.alibaba.com are

mm-userfaultfd-use-swap-in-double_pt_lock.patch