[NEIGH] Print stack trace in neigh_add_timer

Stack traces are very helpful in determining the exact nature of a bug.
So let's print a stack trace when the timer is added twice.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 4128fc76ac3a..766caa0dd930 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -732,6 +732,7 @@ static inline void neigh_add_timer(struct neighbour *n, unsigned long when)
         if (unlikely(mod_timer(&n->timer, when))) {
                 printk("NEIGH: BUG, double timer add, state is %x\n",
                        n->nud_state);
+                dump_stack();
         }
 }