Commit 1954c4f01220 for kernel
commit 1954c4f012206147c34acda8da04f827aa7d3ee3
Author: Eric Dumazet <edumazet@google.com>
Date: Sat Mar 7 20:07:15 2026 +0000
eventpoll: Convert epoll_put_uevent() to scoped user access
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>
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) {
+ unsafe_put_user(revents, &uevent->events, efault);
+ unsafe_put_user(data, &uevent->data, efault);
+ }
return uevent+1;
+
+efault:
+ return NULL;
}
#endif