pkt_sched: Fix qdisc state in net_tx_action()

net_tx_action() can skip __QDISC_STATE_SCHED bit clearing while qdisc
is neither ran nor rescheduled, which may cause endless loop in
dev_deactivate().

Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Tested-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 60c51f765887..e719ed29310f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1991,8 +1991,13 @@ static void net_tx_action(struct softirq_action *h)
                                 spin_unlock(root_lock);
                         } else {
                                 if (!test_bit(__QDISC_STATE_DEACTIVATED,
-                                              &q->state))
+                                              &q->state)) {
                                         __netif_reschedule(q);
+                                } else {
+                                        smp_mb__before_clear_bit();
+                                        clear_bit(__QDISC_STATE_SCHED,
+                                                  &q->state);
+                                }
                         }
                 }
         }