datapath: Reduce loop limit by one to 4.

We currently allow five trips through the kernel datapath
before dropping the packet to protect the stack.  However, there
have been a few reports recently involving tunneling that this is
still too much.  Although it's not a complete solution, this reduces
the limit by one to balance safety in common situations with
flexibility.

Bug #15477

Reported-by: Paul Ingram <paul@nicira.com>
Reported-by: 謝秉融 <faithfulman@gmail.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>

diff --git a/datapath/actions.c b/datapath/actions.c
index bc126a7..0dac658 100644 (file)
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -532,7 +532,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 
 /* We limit the number of times that we pass into execute_actions()
  * to avoid blowing out the stack in the event that we have a loop. */
-#define MAX_LOOPS 5
+#define MAX_LOOPS 4
 
 struct loop_counter {
        u8 count;               /* Count. */