linux-kernel - [PATCH AUTOSEL 4.9 2/3] arm64: psci: Avoid printing in cpu_psci_cpu

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Message-Id: <20201117125759.600148-2-sashal@kernel.org>
Date:   Tue, 17 Nov 2020 07:57:58 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Will Deacon <will@...nel.org>, Qian Cai <cai@...hat.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Sasha Levin <sashal@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.9 2/3] arm64: psci: Avoid printing in cpu_psci_cpu_die()

From: Will Deacon <will@...nel.org>

[ Upstream commit 891deb87585017d526b67b59c15d38755b900fea ]

cpu_psci_cpu_die() is called in the context of the dying CPU, which
will no longer be online or tracked by RCU. It is therefore not generally
safe to call printk() if the PSCI "cpu off" request fails, so remove the
pr_crit() invocation.

Cc: Qian Cai <cai@...hat.com>
Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Link: https://lore.kernel.org/r/20201106103602.9849-2-will@kernel.org
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/kernel/psci.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index e3713d6fb8e00..bf6142a80cf1a 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -68,7 +68,6 @@ static int cpu_psci_cpu_disable(unsigned int cpu)
 
 static void cpu_psci_cpu_die(unsigned int cpu)
 {
-	int ret;
 	/*
 	 * There are no known implementations of PSCI actually using the
 	 * power state field, pass a sensible default for now.
@@ -76,9 +75,7 @@ static void cpu_psci_cpu_die(unsigned int cpu)
 	u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
 		    PSCI_0_2_POWER_STATE_TYPE_SHIFT;
 
-	ret = psci_ops.cpu_off(state);
-
-	pr_crit("unable to power off CPU%u (%d)\n", cpu, ret);
+	psci_ops.cpu_off(state);
 }
 
 static int cpu_psci_cpu_kill(unsigned int cpu)
-- 
2.27.0