[PATCH 5.19 0150/1157] arm64: stacktrace: use non-atomic __set_bit

Greg Kroah-Hartman
2022-08-15T22:38:06Z

From: Andrey Konovalov <andreyknvl@google.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@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Link: https://lore.kernel.org/r/23dfa36d1cc91e4a1059945b7834eac22fb9854d.1653317461.git.andreyknvl@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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