Re: sctp: hang in sctp_remaddr_seq_show

[Vlad Yasevich]

On 03/18/2013 11:25 AM, Eric Dumazet wrote:
> On Mon, 2013-03-18 at 07:04 -0400, Neil Horman wrote:
>
> > I'm not sure why the process would never get back to the schedule, but looking
> > at the sctp_remaddr_seq_show function, I think that we should convert this
> > sequence:
> > 	sctp_local_bh_disable();
> > 	read_lock(&head->lock);
> > 	rcu_read_lock();
> >
> > to this:
> > 	read_lock(&head->lock);
> > 	rcu_read_lock_bh();
> >
> > Neil
>
> I dont think so.
>
> BH needs to be disabled before read_lock(&head->lock);
>
> or else, write_lock() could deadlock (assuming it can be called from BH)

If anything, this should probably be done like this:

rcu_read_lock();
read_lock_bh(&head->lock)
...

read_unlock_bh(&head->lock)
rcu_read_unlock();

-vlad
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