[NETPOLL] netconsole: fix soft lockup when removing module

#1
Until kernel ver. 2.6.21 (including) cancel_rearming_delayed_work()
required a work function should always (unconditionally) rearm with
delay > 0 - otherwise it would endlessly loop. This patch replaces
this function with cancel_delayed_work(). Later kernel versions don't
require this, so here it's only for uniformity.

#2
After deleting a timer in cancel_[rearming_]delayed_work() there could
stay a last skb queued in npinfo->txq causing a memory leak after
kfree(npinfo).

Initial patch & testing by: Jason Wessel <jason.wessel@windriver.com>

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index f8e74e511ce6..cf40ff91ac01 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -72,7 +72,8 @@ static void queue_process(struct work_struct *work)
                         netif_tx_unlock(dev);
                         local_irq_restore(flags);
 
-                        schedule_delayed_work(&npinfo->tx_work, HZ/10);
+                        if (atomic_read(&npinfo->refcnt))
+                                schedule_delayed_work(&npinfo->tx_work, HZ/10);
                         return;
                 }
                 netif_tx_unlock(dev);
@@ -785,9 +786,15 @@ void netpoll_cleanup(struct netpoll *np)
                         if (atomic_dec_and_test(&npinfo->refcnt)) {
                                 skb_queue_purge(&npinfo->arp_tx);
                                 skb_queue_purge(&npinfo->txq);
-                                cancel_rearming_delayed_work(&npinfo->tx_work);
+                                cancel_delayed_work(&npinfo->tx_work);
                                 flush_scheduled_work();
 
+                                /* clean after last, unfinished work */
+                                if (!skb_queue_empty(&npinfo->txq)) {
+                                        struct sk_buff *skb;
+                                        skb = __skb_dequeue(&npinfo->txq);
+                                        kfree_skb(skb);
+                                }
                                 kfree(npinfo);
                         }
                 }