Re: [PATCH] mac80211: check for existance sta before adding it

["Luis R. Rodriguez" <lrodriguez@atheros.com>]

On Wed, Jun 03, 2009 at 11:23:43AM -0700, Johannes Berg wrote:
> On Wed, 2009-06-03 at 11:08 -0700, Luis R. Rodriguez wrote:
> > On Wed, Jun 03, 2009 at 12:00:50AM -0700, Johannes Berg wrote:
> > > On Tue, 2009-06-02 at 14:01 -0700, Luis R. Rodriguez wrote:
> > > 
> > > > Thanks, yeah I see where I was making an incorrect assumption here.
> > > > 
> > > > There still is a case here where userpsace can try to add a sta twice
> > > > and the second parameters passed would be ignored.
> > > 
> > > Don't we show that -EEXIST to userspace then? I thought we did.
> > 
> > We do, but why don't we *first* try to check for its existence?
> 
> Because that's racy -- after the check completes and before we go try to
> insert a station might have come to life. Well, it might actually be ok
> due to external factors (AP mode _only_ gets stations from userspace)
> but it seems better to not rely on that.

I see.

> What problem were you trying to solve btw?

Nothing in particular, I was just reviewing sta code path.

  Luis