Re: [PATCH 6.18.y 1/2] rculist: add list_splice_rcu() for private lists

[Benjamin Robin <benjamin.robin@bootlin.com>]

On Friday, September 25, 2026 at 4:28 PM, Benjamin Robin wrote:
> On Friday, September 25, 2026 at 4:23 PM, Greg KH wrote:
> > On Fri, Sep 25, 2026 at 09:52:23AM +0200, Benjamin Robin (Schneider Electric) wrote:
> > > From: Pablo Neira Ayuso <pablo@netfilter.org>
> > > 
> > > [ Upstream commit f902877b635551513729bdf9a8d1422c4aab7741 ]
> > > 
> > > This patch adds a helper function, list_splice_rcu(), to safely splice
> > > a private (non-RCU-protected) list into an RCU-protected list.
> > > 
> > > The function ensures that only the pointer visible to RCU readers
> > > (prev->next) is updated using rcu_assign_pointer(), while the rest of
> > > the list manipulations are performed with regular assignments, as the
> > > source list is private and not visible to concurrent RCU readers.
> > > 
> > > This is useful for moving elements from a private list into a global
> > > RCU-protected list, ensuring safe publication for RCU readers.
> > > Subsystems with some sort of batching mechanism from userspace can
> > > benefit from this new function.
> > > 
> > > The function __list_splice_rcu() has been added for clarity and to
> > > follow the same pattern as in the existing list_splice*() interfaces,
> > > where there is a check to ensure that the list to splice is not
> > > empty. Note that __list_splice_rcu() has no documentation for this
> > > reason.
> > > 
> > > Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> > > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > > ---
> > >  include/linux/rculist.h | 29 +++++++++++++++++++++++++++++
> > >  1 file changed, 29 insertions(+)
> > 
> > You did not sign off on this commit :(
> 
> Hello Greg,
> 
> Sorry about that, I was not sure about the rule if I did not modify
> the commit in any way.
> I will send a v2 for all branches ASAP (but I may only send the v2
> on Monday).

I have an additional question, I was wondering if it is necessary
to add in CC: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org, ...
These emails were auto suggested, so I kept them. But since I am
sending to stable, maybe I don't need to "spam" everybody.

Again sorry about that, and thank in advance.

-- 
Benjamin Robin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com