Re: [PATCH] Prevent netpoll hanging when link is down

[Andi Kleen <ak@xxxxxxx>]

On Mon, Oct 11, 2004 at 11:22:24AM -0500, Matt Mackall wrote:
> On Mon, Oct 11, 2004 at 05:40:00PM +0200, Andi Kleen wrote:
> > On Sun, Oct 10, 2004 at 08:59:28PM -0700, David S. Miller wrote:
> > > 
> > > Wait, I think I see the problem.
> > > 
> > > Sungem processes link status in it's ->poll() NAPI handler.
> > > This occurs via calls to gem_pcs_interrupt(), for example.
> > > Non-pcs sungem variants use a timer to poll link status.
> > > 
> > > When the link changes state, this link state processing
> > > does printk()'s.
> > > 
> > > So perhaps that is why it deadlocks.
> > 
> > printk handles recursion with the down_trylock on console_sem.
> > So it shouldn't deadlock.
> 
> If we're in the ->poll() handler for non-netpoll reasons, and the link
> state changes, causing a printk, we'll potentially reenter ->poll() via
> netconsole.

It won't because printk catches the case.

-Andi