Re: Race condition between driver_probe_device and device_shutdownâ

[Greg KH]

On Thu, May 24, 2012 at 09:39:46AM +0800, Ming Lei wrote:
> On Wed, May 23, 2012 at 11:06 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Wed, 23 May 2012, Ming Lei wrote:
> >> The .shutdown callback pointer is got from device->driver, which is
> >> changed in probe and release path. Also runtime PM thing has been
> >> involved into shutting down recently, so looks not only hardware parts
> >> are involved now.
> >
> > This is a tricky question.  Overall I think you're probably right.
> >
> > It's certainly true that holding the device lock across the shutdown
> > callback is the easiest and most reliable way to prevent these races.
> 
> But holding device lock across .shutdown is very inefficient because
> most of devices' driver have not shutdown callback, so I think it is better
> to fix the race by prevent driver core from probing or releasing once
> shutdown is started.
> 
> How about the below patch?

How about waiting for the original poster to respond as to exactly how
they are hitting this race before doing anything?

greg k-h
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