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eventpoll: Convert epoll_put_uevent() to scoped user access

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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@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Dumazet
2026-03-07 20:07:15 +00:00
committed by Linus Torvalds
parent 3b5d535c63
commit 1954c4f012
1 changed files with 7 additions and 4 deletions
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11
include/linux/eventpoll.h
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@@ -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) {
unsafe_put_user(revents, &uevent->events, efault);
unsafe_put_user(data, &uevent->data, efault);
}
return uevent+1;
efault:
return NULL;
}
#endif