[NET]: Fix races in net_rx_action vs netpoll.

[powerpc.git] / net / core / netpoll.c

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index de1b26a..d1264e9 100644 (file)
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -124,6 +124,13 @@ static void poll_napi(struct netpoll *np)
        if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
            npinfo->poll_owner != smp_processor_id() &&
            spin_trylock(&npinfo->poll_lock)) {
+               /* When calling dev->poll from poll_napi, we may end up in
+                * netif_rx_complete. However, only the CPU to which the
+                * device was queued is allowed to remove it from poll_list.
+                * Setting POLL_LIST_FROZEN tells netif_rx_complete
+                * to leave the NAPI state alone.
+                */
+               set_bit(__LINK_STATE_POLL_LIST_FROZEN, &np->dev->state);
                npinfo->rx_flags |= NETPOLL_RX_DROP;
                atomic_inc(&trapped);
 
@@ -131,6 +138,7 @@ static void poll_napi(struct netpoll *np)
 
                atomic_dec(&trapped);
                npinfo->rx_flags &= ~NETPOLL_RX_DROP;
+               clear_bit(__LINK_STATE_POLL_LIST_FROZEN, &np->dev->state);
                spin_unlock(&npinfo->poll_lock);
        }
 }