Re: [PATCH 1/5] eventpoll: Convert epoll_put_uevent() to scoped user access

[Eric Dumazet]

On Tue, Mar 10, 2026 at 9:29 AM Christophe Leroy (CS GROUP)
<chleroy@xxxxxxxxxx> wrote:
>
>
>
> Le 10/03/2026 à 08:54, renpanpan a écrit :
> > [Vous ne recevez pas souvent de courriers de renpanpan@xxxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> >
> > From: Eric Dumazet <edumazet@xxxxxxxxxx>
> >
> > Saves two function calls, and one stac/clac pair.
> >
> > stac/clac is rather expensive on older cpus like Zen 2.
> >
> > A synthetic network stress test gives a ~1.5% increase of pps
> > on AMD Zen 2.
> >
> > Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> > Cc: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> > ---
> >   include/linux/eventpoll.h | 11 +++++++----
> >   1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
> > index ccb478eb174b..ea9ca0e4172a 100644
> > --- a/include/linux/eventpoll.h
> > +++ b/include/linux/eventpoll.h
> > @@ -82,11 +82,14 @@ static inline struct epoll_event __user *
> >   epoll_put_uevent(__poll_t revents, __u64 data,
> >                   struct epoll_event __user *uevent)
> >   {
> > -       if (__put_user(revents, &uevent->events) ||
> > -           __put_user(data, &uevent->data))
> > -               return NULL;
> > -
> > +       scoped_user_write_access_size(uevent, sizeof(*uevent), efault) {
>
> As already mentionned this could be simplified:

Note the patch was already merged in Linus tree.

Honestly having two different macros while we have 4 users for both
of them seems a bit overkill to me.