linux-kernel - [PATCH 4.15 32/64] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise

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Message-Id: <20180226202154.827569198@linuxfoundation.org>
Date:   Mon, 26 Feb 2018 21:22:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Shanker Donthineni <shankerd@...eaurora.org>,
        Marc Zyngier <marc.zyngier@....com>
Subject: [PATCH 4.15 32/64] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise_softirq()

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shanker Donthineni <shankerd@...eaurora.org>

commit 21ec30c0ef5234fb1039cc7c7737d885bf875a9e upstream.

A DMB instruction can be used to ensure the relative order of only
memory accesses before and after the barrier. Since writes to system
registers are not memory operations, barrier DMB is not sufficient
for observability of memory accesses that occur before ICC_SGI1R_EL1
writes.

A DSB instruction ensures that no instructions that appear in program
order after the DSB instruction, can execute until the DSB instruction
has completed.

Cc: stable@...r.kernel.org
Acked-by: Will Deacon <will.deacon@....com>,
Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/irqchip/irq-gic-v3.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -688,7 +688,7 @@ static void gic_raise_softirq(const stru
 	 * Ensure that stores to Normal memory are visible to the
 	 * other CPUs before issuing the IPI.
 	 */
-	smp_wmb();
+	wmb();
 
 	for_each_cpu(cpu, mask) {
 		u64 cluster_id = MPIDR_TO_SGI_CLUSTER_ID(cpu_logical_map(cpu));