Commit 1954c4f0 authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds
Browse files

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: default avatarEric 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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3b5d535c

include/linux/eventpoll.h

+7 −4
Original line number Diff line number Diff line
@@ -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