Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Andrey Konovalov <andreyknvl@google.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Will Deacon <will@kernel.org>, Sasha Levin <sashal@kernel.org>,
        catalin.marinas@arm.com, broonie@kernel.org,
        kaleshsingh@google.com, madvenka@linux.microsoft.com,
        mhiramat@kernel.org, andreyknvl@gmail.com, maz@kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 5.19 04/58] arm64: stacktrace: use non-atomic __set_bit
Date:   Sun,  7 Aug 2022 21:30:22 -0400
Message-Id: <20220808013118.313965-4-sashal@kernel.org>
In-Reply-To: <20220808013118.313965-1-sashal@kernel.org>
References: <20220808013118.313965-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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