[NET]: Fix race between poll_napi() and net_rx_action()

[profile/ivi/kernel-adaptation-intel-automotive.git] / net / core / netpoll.c

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index bf8d18f..c499b5c 100644 (file)
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -116,6 +116,29 @@ static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
  * network adapter, forcing superfluous retries and possibly timeouts.
  * Thus, we set our budget to greater than 1.
  */
+static int poll_one_napi(struct netpoll_info *npinfo,
+                        struct napi_struct *napi, int budget)
+{
+       int work;
+
+       /* net_rx_action's ->poll() invocations and our's are
+        * synchronized by this test which is only made while
+        * holding the napi->poll_lock.
+        */
+       if (!test_bit(NAPI_STATE_SCHED, &napi->state))
+               return budget;
+
+       npinfo->rx_flags |= NETPOLL_RX_DROP;
+       atomic_inc(&trapped);
+
+       work = napi->poll(napi, budget);
+
+       atomic_dec(&trapped);
+       npinfo->rx_flags &= ~NETPOLL_RX_DROP;
+
+       return budget - work;
+}
+
 static void poll_napi(struct netpoll *np)
 {
        struct netpoll_info *npinfo = np->dev->npinfo;
@@ -123,17 +146,13 @@ static void poll_napi(struct netpoll *np)
        int budget = 16;
 
        list_for_each_entry(napi, &np->dev->napi_list, dev_list) {
-               if (test_bit(NAPI_STATE_SCHED, &napi->state) &&
-                   napi->poll_owner != smp_processor_id() &&
+               if (napi->poll_owner != smp_processor_id() &&
                    spin_trylock(&napi->poll_lock)) {
-                       npinfo->rx_flags |= NETPOLL_RX_DROP;
-                       atomic_inc(&trapped);
-
-                       napi->poll(napi, budget);
-
-                       atomic_dec(&trapped);
-                       npinfo->rx_flags &= ~NETPOLL_RX_DROP;
+                       budget = poll_one_napi(npinfo, napi, budget);
                        spin_unlock(&napi->poll_lock);
+
+                       if (!budget)
+                               break;
                }
        }
 }