On Tue, 2010-11-23 at 07:51 +0200, Juuso Oikarinen wrote:
> On Mon, 2010-11-22 at 14:52 +0200, Luciano Coelho wrote:
> > On Thu, 2010-11-18 at 15:19 +0200, juuso.oikarinen@xxxxxxxxx wrote:
> > > From: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx>
> > >
> > > It is possible that the op_remove_interface function is invoked exactly at
> > > the same time has hw recovery is started. In this case it is possible for the
> > > interface to be already removed in the op_remove_interface call, which
> > > currently leads to a kernel warning and a subsequent kernel crash.
> > >
> > > Fix this by ignoring the op_remove_interface call if the interface is already
> > > down at that point.
> > >
> > > Signed-off-by: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx>
> > > ---
> >
> > [...]
> >
> > > diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
> > > index 31f0e2f..11b0477 100644
> > > --- a/drivers/net/wireless/wl12xx/main.c
> > > +++ b/drivers/net/wireless/wl12xx/main.c
> > > @@ -1157,10 +1157,16 @@ static void wl1271_op_remove_interface(struct ieee80211_hw *hw,
> > > struct wl1271 *wl = hw->priv;
> > >
> > > mutex_lock(&wl->mutex);
> > > - WARN_ON(wl->vif != vif);
> > > - __wl1271_op_remove_interface(wl);
> > > - mutex_unlock(&wl->mutex);
> > > + /*
> > > + * wl->vif can be null here if someone shuts down the interface
> > > + * just when hardware recovery has been started.
> > > + */
> > > + if (wl->vif) {
> > > + WARN_ON(wl->vif != vif);
> > > + __wl1271_op_remove_interface(wl);
> > > + }
> >
> > Should you still remove the interface if the vif you received is wrong?
> > Surely, something is totally wrong if you get a different vif, but maybe
> > removing the interface here will just confuse things even more?
>
> Dunno if it would be better to remove or leave unremoved - probably does
> not matter. If the vif is wrong, there is some serious bug somewhere,
> and probably the result is serious instability anyway.
>
> The WARN_ON is there just to validate the assumption the driver makes
> about the vif, and this function call. If there is a bug somewhere, or
> the assumption somehow changes, the warning will be a clear indication
> of it.
Yep, it's okay like this. And it was like that earlier anyway. I was
just wondering if it would be possible for a similar thing as wl->vif
being NULL (which your patch addresses) happen, such as wl->vif changing
before we had the chance to fully remove the interface. It will
probably not happen and, as you say, the WARN_ON will be a good
indication that something went wrong.
Applied to wl12xx/master. Thanks!
--
Cheers,
Luca.
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