linux-kernel - [tip: perf/core] mm/gup: Use raw_seqcount_try

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Message-ID: <173313805159.412.6588100615473123377.tip-bot2@tip-bot2>
Date: Mon, 02 Dec 2024 11:14:11 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: David Hildenbrand <david@...hat.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: perf/core] mm/gup: Use raw_seqcount_try_begin()

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@...radead.org>
AuthorDate:    Fri, 22 Nov 2024 12:47:48 +01:00
Committer:     Peter Zijlstra <peterz@...radead.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@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: David Hildenbrand <david@...hat.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;
 	}