Subject: Re: linux-next: build failure after merge of the rcu tree

From: Stephen Rothwell <[email-masked]>
Date: Thu, 12 Dec 2019 15:26:13 +1100

Hi Paul,

On Wed, 11 Dec 2019 20:07:37 -0800 "Paul E. McKenney" <[email-masked]> wrote:
>
> On Thu, Dec 12, 2019 at 01:45:16PM +1100, Stephen Rothwell wrote:
> > Hi all,
> > 
> > After merging the rcu tree, today's linux-next build (x86_64 allmodconfig)
> > failed like this:
> > 
> > drivers/misc/watch_queue.c: In function 'watch_queue_set_filter':
> > drivers/misc/watch_queue.c:526:2: error: implicit declaration of function 'rcu_swap_protected' [-Werror=implicit-function-declaration]
> >   526 |  rcu_swap_protected(wqueue->filter, wfilter,
> >       |  ^~~~~~~~~~~~~~~~~~
> > 
> > Caused by commit
> > 
> >   af8c9224182e ("rcu: Remove rcu_swap_protected()")
> > 
> > interacting with commit
> > 
> >   fe78d401ca6b ("General notification queue with user mmap()'able ring buffer")
> > 
> > from the keys tree.
> > 
> > I have added the following merge fix patch for today:
> > 
> > From: Stephen Rothwell <[email-masked]>
> > Date: Thu, 12 Dec 2019 13:37:52 +1100
> > Subject: [PATCH] rcu: fix up for "Remove rcu_swap_protected()"
> > 
> > Signed-off-by: Stephen Rothwell <[email-masked]>  
> 
> Reviewed-by: Paul E. McKenney <[email-masked]>

Thanks.

> I would be happy to take this if desired, but it would probably be better
> for this to be applied directly to the keys tree.  Either way, please let
> me know.

Well, you can't take this fix up without merging the keys tree ... and
the keys tree is currently in flux so it should be easy for it to be
applied there since rcu_replace_pointer() already exists in Linus'
tree, right?.

-- 
Cheers,
Stephen Rothwell