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

[任盼盼]

 

Upon re-examining the code, I see that it would indeed introduce new issues.
That was an oversight on my part. Thanks for pointing that out.

主   题：Re: [PATCH 1/5] eventpoll: Convert epoll_put_uevent() to scoped user access
日   期：2026年03月10日22:30
发件人：David Laight
收件人：Christophe Leroy (CS GROUP),David Laight
抄送人：Eric Dumazet,linux-kernel,Dave Hansen,Kuniyuki Iwashima,Linus Torvalds

On Tue, 10 Mar 2026 11:25:48 +0100 "Christophe Leroy (CS GROUP)" <chleroy@xxxxxxxxxx> wrote: > Le 10/03/2026 à 09:32, Eric Dumazet a écrit : > > 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. > > There have at the time beeing (v7.0-rc3) 66 caller of > user_...access_begin(), I expect most of them being converted to scoped > user access over time. In addition the simplicity of scoped user access > should help grow the numbre of users of user access by block. > > I find it quite convenient to not have to add the size when it can be > extracted from the pointer type. Lets see if it possible to support both: foo(ptr, label) and: foo(ptr, size, label) #define foo(p, ...) foo_1(p, __VA_ARGS__, sizeof *p) #define foo_1(p, s_or_l, l_or_ps, ...) \ foo_2(p, __VA_OPT__(s_or_l, l_or_ps, foo_x(__VA_ARGS__)) l_or_ps, s_or_pl) #define foo_x(one_arg) #define foo_2(p, s, l, ...) foo_real(p, s, l) untested - but might work! (foo_x() is there to error foo(a, b, c, d)) David > > Christophe > </torvalds@xxxxxxxxxxxxxxxxxxxx></kuniyu@xxxxxxxxxx></dave.hansen@xxxxxxxxx></christophe.leroy@xxxxxxxxxx></edumazet@xxxxxxxxxx></edumazet@xxxxxxxxxx></chleroy@xxxxxxxxxx></chleroy@xxxxxxxxxx>

 

 

 

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