[merged mm-stable] mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending
has been removed from the -mm tree.  Its filename was
     mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Uros Bizjak <ubizjak@gmail.com>
Subject: mm/rmap: use atomic_try_cmpxchg in set_tlb_ubc_flush_pending
Date: Mon, 27 Feb 2023 22:42:28 +0100

Use atomic_try_cmpxchg instead of atomic_cmpxchg (*ptr, old, new) == old
in set_tlb_ubc_flush_pending.  86 CMPXCHG instruction returns success in
ZF flag, so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).

Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails.

No functional change intended.

Link: https://lkml.kernel.org/r/20230227214228.3533299-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/rmap.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/mm/rmap.c~mm-rmap-use-atomic_try_cmpxchg-in-set_tlb_ubc_flush_pending
+++ a/mm/rmap.c
@@ -644,7 +644,7 @@ void try_to_unmap_flush_dirty(void)
 static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
 {
 	struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
-	int batch, nbatch;
+	int batch;
 
 	arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
 	tlb_ubc->flush_required = true;
@@ -662,11 +662,8 @@ retry:
 		 * overflow.  Reset `pending' and `flushed' to be 1 and 0 if
 		 * `pending' becomes large.
 		 */
-		nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1);
-		if (nbatch != batch) {
-			batch = nbatch;
+		if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1))
 			goto retry;
-		}
 	} else {
 		atomic_inc(&mm->tlb_flush_batched);
 	}
_

Patches currently in -mm which might be from ubizjak@gmail.com are

nfs-remove-empty-if-statement-from-nfs3_prepare_get_acl.patch