Re: [PATCH]generic usb serial driver

On Fri, Mar 30, 2007 at 10:45:26AM +0200, Oliver Neukum wrote:
> Am Freitag, 30. M?rz 2007 10:39 schrieb Greg KH:
> > > To solve this with locking would require both CPU A and CPU B to take
> > > the lock, which means that the urb would have to be submitted with
> > > GFP_ATOMIC.
> > 
> > Can't this all be solved with a simple:
> > 
> > ????????get port spinlock
> > ????????a = urb->status
> > ????????write_busy = 0
> > ????????unlock spinlock
> > 
> > In the callback, and in the write path:
> > 
> > ????????get port spinlock
> > ????????if write_busy
> > ????????????????unlock
> > ????????????????exit
> > ????????write_busy = 1
> > ????????unlock port spinlock
> > ????????submit_urb
> > 
> 
> Oops. You are right. That would work.
> If you think that's simpler, yes it can be done.

Yes, I think that would be both easier to understand, and easier to
prove correct :)

thanks,

greg k-h

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