linux-kernel - [PATCH v2 05/10] ARM: bcm: don't special-case CPU 0 in bcm_kona

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Date:	Mon, 21 Apr 2014 16:53:06 -0500
From:	Alex Elder <elder@...aro.org>
To:	bcm@...thebug.org, mporter@...aro.org
Cc:	bcm-kernel-feedback-list@...adcom.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 05/10] ARM: bcm: don't special-case CPU 0 in bcm_kona_smc()

There's logic in bcm_kona_smc() to ensure __bcm_kona_smc() gets
called on CPU 0; if already executing on CPU 0, that function is
called directly.  The direct call is not protected from interrupts,
however, which is not safe.

Note that smp_call_function_single() is designed to handle the case
where the target cpu is the current one.  It also gets a reference
to the CPU and disables IRQs across the call.

So we can simplify things and at the same time be protected against
interrupts by calling smp_call_function_single() unconditionally.

Signed-off-by: Alex Elder <elder@...aro.org>
Reviewed-by: Tim Kryger <tim.kryger@...aro.org>
Reviewed-by: Markus Mayer <markus.mayer@...aro.org>
Reviewed-by: Matt Porter <mporter@...aro.org>
---
 arch/arm/mach-bcm/bcm_kona_smc.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/arm/mach-bcm/bcm_kona_smc.c b/arch/arm/mach-bcm/bcm_kona_smc.c
index 47cf360..6fdcf96 100644
--- a/arch/arm/mach-bcm/bcm_kona_smc.c
+++ b/arch/arm/mach-bcm/bcm_kona_smc.c
@@ -114,12 +114,7 @@ unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
 	 * Due to a limitation of the secure monitor, we must use the SMP
 	 * infrastructure to forward all secure monitor calls to Core 0.
 	 */
-	if (get_cpu() != 0)
-		smp_call_function_single(0, __bcm_kona_smc, (void *)&data, 1);
-	else
-		__bcm_kona_smc(&data);
-
-	put_cpu();
+	smp_call_function_single(0, __bcm_kona_smc, &data, 1);
 
 	return data.result;
 }
-- 
1.9.1

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