Messages in this thread | | | From | Markus Pargmann <> | Subject | Re: [PATCH 1/4] nbd: Remove signal usage | Date | Tue, 10 Nov 2015 11:22:45 +0100 |
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Hi,
On Tuesday 10 November 2015 04:46:18 Al Viro wrote: > On Thu, Oct 29, 2015 at 04:42:37PM +0100, Markus Pargmann wrote: > > del_timer_sync(&nbd->timeout_timer); > > + > > +out: > > + spin_unlock_irq(&nbd->sock_lock); > > ... and in its callback we have this: > > > @@ -148,17 +155,15 @@ static void nbd_xmit_timeout(unsigned long arg) > > > > nbd->disconnect = true; > > > > - spin_lock_irqsave(&nbd->tasks_lock, flags); > > + spin_lock_irqsave(&nbd->sock_lock, flags); > > * CPU 1 enters sock_shutdown() and grabs ->sock_lock. > * on CPU2 the timer hits and we enter the callback, where we spin on that > spinlock. > * in the meanwhile, CPU1 calls del_timer_sync() > > Deadlock...
Thank you. Yes that locking block in sock_shutdown is to large. And probably the del_timer_sync() isn't necessary, we can just use del_timer().
It may even be possible to remove the sock_lock completely. Will look into this and post a v2.
Thanks,
Markus
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