MIPS: CMP: Fix memory barriers for correct operation of amon_cpu_start

Signed-off-by: Chris Dearman (chris@mips.com)
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/mips/mti-malta/malta-amon.c b/arch/mips/mti-malta/malta-amon.c
index df9e526312a2..469d9b0cee6d 100644
--- a/arch/mips/mti-malta/malta-amon.c
+++ b/arch/mips/mti-malta/malta-amon.c
@@ -70,11 +70,12 @@ void amon_cpu_start(int cpu,
         launch->sp = sp;
         launch->a0 = a0;
 
-        /* Make sure target sees parameters before the go bit */
-        smp_mb();
-
+        smp_wmb();              /* Target must see parameters before go */
         launch->flags |= LAUNCH_FGO;
+        smp_wmb();              /* Target must see go before we poll  */
+
         while ((launch->flags & LAUNCH_FGONE) == 0)
                 ;
+        smp_rmb();      /* Target will be updating flags soon */
         pr_debug("launch: cpu%d gone!\n", cpu);
 }