linux-kernel - [PATCH V2 1/2] MIPS: smp: Make stop_this

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Date:	Wed, 25 Mar 2015 10:25:43 -0700
From:	Andrew Bresticker <abrestic@...omium.org>
To:	Ralf Baechle <ralf@...ux-mips.org>
Cc:	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
	Andrew Bresticker <abrestic@...omium.org>,
	James Hogan <james.hogan@...tec.com>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>
Subject: [PATCH V2 1/2] MIPS: smp: Make stop_this_cpu() actually stop the CPU

Since cpu_wait() enables interrupts upon return, CPUs which have
entered stop_this_cpu() may still end up handling interrupts.
This can lead to the softlockup detector firing on a panic or
restart/poweroff/halt.  Just disable interrupts and spin to ensure
nothing else runs on the CPU once it has entered stop_this_cpu().

Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
Cc: James Hogan <james.hogan@...tec.com>
Cc: Maciej W. Rozycki <macro@...ux-mips.org>
---
New for v2.
---
 arch/mips/kernel/smp.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 1c0d8c5..5b020bd 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -176,10 +176,8 @@ static void stop_this_cpu(void *dummy)
 	 * Remove this CPU:
 	 */
 	set_cpu_online(smp_processor_id(), false);
-	for (;;) {
-		if (cpu_wait)
-			(*cpu_wait)();		/* Wait if available. */
-	}
+	local_irq_disable();
+	while (1);
 }
 
 void smp_send_stop(void)
-- 
2.2.0.rc0.207.ga3a616c

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