From: Greg KH <greg@kroah.com>
To: linux-hotplug@vger.kernel.org
Subject: Re: [PATCH] USB hotplug race
Date: Sat, 27 Mar 2004 00:12:17 +0000 [thread overview]
Message-ID: <20040327001217.GA11946@kroah.com> (raw)
In-Reply-To: <20040317142717.GA14149@pasky.ji.cz>
On Sat, Mar 27, 2004 at 01:05:52AM +0100, Oliver Neukum wrote:
>
> > > After populating the hotplug scripts with plethora of debug prints,
> > > I've tracked it down to usb_convert_vars() - basically, immediatelly
> > > after the USB device is plugged and the signal is already delivered to
> > > hotplug, the sysfs tree isn't yet populated by all the relevant data
> > > and only detach_state is present there - no bDeviceClass or so.
> >
> > Yes, it's quite easy to race the kernel with this. But how about
> > putting the proper patch in by sitting and spinning until we see the
> > file we are looking for (or erroring out after a time period.)
> >
> > That's much cleaner than always sleeping. On a SMP box, you usually
> > never need to sleep :)
>
> It seems to me the proper patch would be for the kernel to wait for
> the creation of any files it refers to when generating a hotplug invocation.
Heh, yeah, that would be "nice" to have, but unfortunatly due to the way
the stupid stupid stupid programmer [1] who wrote that code, it's quite
difficult (if not impossible) to do...
It's a 2.7 thing...
thanks,
greg k-h
[1] yeah, it was me, go ahead, blame me, who knew hotplug would be so
fast...
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prev parent reply other threads:[~2004-03-27 0:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-17 14:27 [PATCH] USB hotplug race Petr Baudis
2004-03-26 23:05 ` Greg KH
2004-03-27 0:05 ` Oliver Neukum
2004-03-27 0:12 ` Greg KH [this message]
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