Re: 2.6.7-mm7

Greg KH
2004-07-09T22:23:37Z

On Fri, Jul 09, 2004 at 01:00:45PM -0700, Andrew Morton wrote:
> Jesse Stockall <stockall@magma.ca> wrote:
> >
> > On Fri, 2004-07-09 at 14:54, Andrew Morton wrote:
> > down_write_trylock(&usb_all_devices_rwsem));
> > >
> > > That's a bit unusual. Could you (or Alan) please explain the reason for
> > > this a little more?
> >
> > I believe you want this thread
> >
> > http://marc.theaimsgroup.com/?l=linux-usb-devel&m=108923404032264&w=2
>
> Oh, OK. Recursively taking an rwsem for reading is certainly deadlocky.
> The main reason for not supporting this is that heavy down_read() traffic
> can trivially livelock down_write() waiters. Alan's patch will introduce
> that shortcoming.
>
> Really, it would be better to get the locking sorted out.

I agree, and we will before submitting the code to Linus.

thanks,

greg k-h