Re: [PATCH] tty: annotate tty_lock() for lockdep

[Eric Dumazet]

On Thu, 2012-05-31 at 17:01 +0530, Srikar Dronamraju wrote:
> Hi Jiri, 
> 
> 
> 
> > =============================================
> > [ INFO: possible recursive locking detected ]
> > 3.4.0-08218-gb48b2c3 #7 Not tainted
> > ---------------------------------------------
> > blogd/279 is trying to acquire lock:
> >  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff8150f51e>] tty_lock+0x3e/0x90
> > 
> > but task is already holding lock:
> >  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff8150f51e>] tty_lock+0x3e/0x90
> > 
> > other info that might help us debug this:
> >  Possible unsafe locking scenario:
> > 
> >        CPU0
> >        ----
> >   lock(&tty->legacy_mutex);
> >   lock(&tty->legacy_mutex);
> > 
> >  *** DEADLOCK ***
> > 
> 
> I saw a similar problem and applied your patch, but that doesnt seem to
> help me.

I was not aware of Jiri patch

Try this one instead :

https://lkml.org/lkml/2012/5/31/125



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