[PKT_SCHED] ematch: tcf_em_destroy robustness

Make the code in tcf_em_tree_destroy more robust and cleaner:
 * Don't need to cast pointer to kfree() or avoid passing NULL.
 * After freeing the tree, clear the pointer to avoid possible problems
from repeated free.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/sched/ematch.c b/net/sched/ematch.c
index d421ec728ee7..b29439ddcf71 100644
--- a/net/sched/ematch.c
+++ b/net/sched/ematch.c
@@ -409,14 +409,15 @@ void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree)
                 if (em->ops) {
                         if (em->ops->destroy)
                                 em->ops->destroy(tp, em);
-                        else if (!tcf_em_is_simple(em) && em->data)
-                                kfree((void *) em->data);
+                        else if (!tcf_em_is_simple(em))
+                                kfree(em->data);
                         module_put(em->ops->owner);
                 }
         }
 
         tree->hdr.nmatches = 0;
         kfree(tree->matches);
+        tree->matches = NULL;
 }
 EXPORT_SYMBOL(tcf_em_tree_destroy);