[ARM SMP] Clear the exclusive monitor on ARMv6 CPUs on context switch

Ensure that the exclusive monitor is cleared on context switch with
ARMv6 CPUs.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 39a6c1b..7152bfb 100644 (file)
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -533,6 +533,13 @@ ENTRY(__switch_to)
        ldr     r3, [r2, #TI_TP_VALUE]
        stmia   ip!, {r4 - sl, fp, sp, lr}      @ Store most regs on stack
        ldr     r6, [r2, #TI_CPU_DOMAIN]!
+#if __LINUX_ARM_ARCH__ >= 6
+#ifdef CONFIG_CPU_MPCORE
+       clrex
+#else
+       strex   r3, r4, [ip]                    @ Clear exclusive monitor
+#endif
+#endif
 #if defined(CONFIG_CPU_XSCALE) && !defined(CONFIG_IWMMXT)
        mra     r4, r5, acc0
        stmia   ip, {r4, r5}