[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>

diff --git a/arch/ppc64/kernel/machine_kexec.c b/arch/ppc64/kernel/machine_kexec.c
index 4775f12a013c5b1a728b5f4ef57f81ef4f07e0be..bf7cc4f8210f125b245d1e36b0dd4ec60ef263fc 100644 (file)
--- 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",