Re: patch usb-bus-mutex.patch added to gregkh-2.6 tree

On Tue, Apr 10, 2007 at 12:14:48PM -0400, Alan Stern wrote:
> On Mon, 9 Apr 2007 [email protected] wrote:
> 
> > 
> > This is a note to let you know that I've just added the patch titled
> > 
> >      Subject: USB: remove use of the bus rwsem, as it doesn't really protect anything.
> > 
> > to my gregkh-2.6 tree.  Its filename is
> > 
> >      usb-bus-mutex.patch
> > 
> > This tree can be found at 
> >     http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/
> > 
> > 
> > From foo@baz Tue Apr  9 12:12:43 2002
> > Date: Mon, 9 Apr 2007 11:52:31 -0400 (EDT)
> > To: Greg KH <[email protected]>
> > From: Greg Kroah-Hartman <[email protected]>
> > Subject: USB: remove use of the bus rwsem, as it doesn't really protect anything.
> > 
> > The driver core stopped using the rwsem a long time ago, yet the USB
> > core still grabbed the lock, thinking it protected something.  As a lock
> > is really needed for these instances, I've replaced it with a local
> > mutex to protect the bus, but odds are there is still a code path that
> > needs to have this lock added to it to properly protect things.
> 
> Actually I don't think the new mutex is needed for protecting anything.  
> All the areas covered by your patch are already protected by the device
> lock (changes to bindings, interfaces, or configurations, addition or
> removal of children) or the bus_list_lock (addition or removal of root
> hubs).

Ok, thanks, I thought that might be the case, but wanted to be safe.
I'll just rip it all out instead.

> BTW, there are a couple of references to usb_bus_type.subsys in comments 
> in driver.c.  You might as well remove them too.

Ah, thanks, will do.

greg k-h

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