linux-kernel - [PATCH AUTOSEL 5.19 04/58] arm64: stacktrace: use non-atomic __set

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Date:   Sun,  7 Aug 2022 21:30:22 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Andrey Konovalov <andreyknvl@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will@...nel.org>, Sasha Levin <sashal@...nel.org>,
        catalin.marinas@....com, broonie@...nel.org,
        kaleshsingh@...gle.com, madvenka@...ux.microsoft.com,
        mhiramat@...nel.org, andreyknvl@...il.com, maz@...nel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 5.19 04/58] arm64: stacktrace: use non-atomic __set_bit

From: Andrey Konovalov <andreyknvl@...gle.com>

[ Upstream commit 446297b28a21244e4045026c4599d1b14a67e2ce ]

Use the non-atomic version of set_bit() in arch/arm64/kernel/stacktrace.c,
as there is no concurrent accesses to frame->prev_type.

This speeds up stack trace collection and improves the boot time of
Generic KASAN by 2-5%.

Suggested-by: Mark Rutland <mark.rutland@....com>
Acked-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Link: https://lore.kernel.org/r/23dfa36d1cc91e4a1059945b7834eac22fb9854d.1653317461.git.andreyknvl@google.com
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/kernel/stacktrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index c246e8d9f95b..d6bef106e37e 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -117,7 +117,7 @@ static int notrace unwind_next(struct task_struct *tsk,
 		if (fp <= state->prev_fp)
 			return -EINVAL;
 	} else {
-		set_bit(state->prev_type, state->stacks_done);
+		__set_bit(state->prev_type, state->stacks_done);
 	}
 
 	/*
-- 
2.35.1