[PATCH] powerpc/numa: Handle unitialized timer reset

[Michael Bringmann]

Some of the code in 'numa.c' may be reused when updating kernel
state after an LPAR migration event.  One such common function
is 'reset_topology_timer' which was being invoked by the
'.notifier_call' function within the NUMA module by
'of_property_notify'.  If this occurs after a previous call to
'stop_topology_update' or on a system without VPHN enabled, the
code runs into an unitialized timer structure and crashes.  This
patch adds a safety check along this path toward the problem code.

Signed-off-by: Michael Bringmann <mwb at linux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 57a5029..8802e7d 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1457,7 +1457,8 @@ static void topology_timer_fn(struct timer_list *unused)
 
 static void reset_topology_timer(void)
 {
-	mod_timer(&topology_timer, jiffies + topology_timer_secs * HZ);
+	if (vphn_enabled)
+		mod_timer(&topology_timer, jiffies + topology_timer_secs * HZ);
 }
 
 #ifdef CONFIG_SMP