From: Catalin Marinas <catalin.marinas@arm.com>
Date: Thu, 15 Feb 2007 18:05:29 +0000 (+0100)
Subject: [ARM] 4201/1: SMP barriers pair needed for the secondary boot process
X-Git-Tag: v2.6.21-rc1~75^2~6^6
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e0ba76926c37f11f38670db0cb33728f502551e;p=linux-2.6

[ARM] 4201/1: SMP barriers pair needed for the secondary boot process

In some situations, the pen_release store in platform_secondary_init()
may stay forever in the write buffer while the CPU is waiting on the
boot_lock to be released in boot_secondary(). The primary CPU could
never see the pen_release update without the barriers.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/mach-realview/platsmp.c b/arch/arm/mach-realview/platsmp.c
index 709a9b1ac6..fce3596f99 100644
--- a/arch/arm/mach-realview/platsmp.c
+++ b/arch/arm/mach-realview/platsmp.c
@@ -59,6 +59,7 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
 	 * pen, then head off into the C entry point
 	 */
 	pen_release = -1;
+	smp_wmb();
 
 	/*
 	 * Synchronise with the boot thread.
@@ -102,6 +103,7 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
 
 	timeout = jiffies + (1 * HZ);
 	while (time_before(jiffies, timeout)) {
+		smp_rmb();
 		if (pen_release == -1)
 			break;