[PATCH] Re: [NETPOLL] netconsole: fix soft lockup when removing module

Jarek Poplawski
2007-07-02T07:44:20Z

>From my recent patch:

> > #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.

But Oleg Nesterov <oleg@tv-sign.ru> found:

> But 2.6.22 doesn't need this change, why it was merged?
>
> In fact, I suspect this change adds a race,
...

His description was right (thanks), so this patch reverts #1.

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>

---

diff -Nurp 2.6.22-rc7-/net/core/netpoll.c 2.6.22-rc7/net/core/netpoll.c
--- 2.6.22-rc7-/net/core/netpoll.c 2007-07-02 09:03:27.000000000 +0200
+++ 2.6.22-rc7/net/core/netpoll.c 2007-07-02 09:32:34.000000000 +0200
@@ -72,8 +72,7 @@ static void queue_process(struct work_st
netif_tx_unlock(dev);
local_irq_restore(flags);

- if (atomic_read(&npinfo->refcnt))
- schedule_delayed_work(&npinfo->tx_work, HZ/10);
+ schedule_delayed_work(&npinfo->tx_work, HZ/10);
return;
}
netif_tx_unlock(dev);
@@ -786,7 +785,7 @@ 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_delayed_work(&npinfo->tx_work);
+ cancel_rearming_delayed_work(&npinfo->tx_work);
flush_scheduled_work();

/* clean after last, unfinished work */