The following commit has been merged into the perf/core branch of tip:

Commit-ID:     7528585290a1a1d4e0fb4b72261eb2d8c85de2d7
Gitweb:        https://git.kernel.org/tip/7528585290a1a1d4e0fb4b72261eb2d8c85de2d7
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Fri, 22 Nov 2024 12:47:48 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 02 Dec 2024 12:01:37 +01:00

mm/gup: Use raw_seqcount_try_begin()

David pointed out that gup_fast() does exactly what the new
raw_seqcount_try_begin() does -- use it.

Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 mm/gup.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 746070a..81ffbd8 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3351,8 +3351,7 @@ static unsigned long gup_fast(unsigned long start, unsigned long end,
 		return 0;
 
 	if (gup_flags & FOLL_PIN) {
-		seq = raw_read_seqcount(&current->mm->write_protect_seq);
-		if (seq & 1)
+		if (!raw_seqcount_try_begin(&current->mm->write_protect_seq, seq))
 			return 0;
 	}