[PATCH] ppc64: Add missing barrier() in kexec code

Mikey and I were testing kexec and hit a lockup.  It turns out gcc 4.0
optimises the kexec_prepare_cpus loop so we avoid reloading paca.hw_cpu_id.
 A gcc barrier() fixes the problem.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/machine_kexec.c b/arch/ppc64/kernel/machine_kexec.c
index 4775f12a013c..bf7cc4f8210f 100644
--- a/arch/ppc64/kernel/machine_kexec.c
+++ b/arch/ppc64/kernel/machine_kexec.c
@@ -205,6 +205,7 @@ static void kexec_prepare_cpus(void)
                         continue;
 
                 while (paca[i].hw_cpu_id != -1) {
+                        barrier();
                         if (!cpu_possible(i)) {
                                 printk("kexec: cpu %d hw_cpu_id %d is not"
                                                 " possible, ignoring\n",