6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Frederik Deweerdt <deweerdt.lkml@xxxxxxxxx>
commit 6bd8614fc2d076fc21b7488c9f279853960964e2 upstream.
When `skb_splice_from_iter` was introduced, it inadvertently added
checksumming for AF_UNIX sockets. This resulted in significant
slowdowns, for example when using sendfile over unix sockets.
Using the test code in [1] in my test setup (2G single core qemu),
the client receives a 1000M file in:
- without the patch: 1482ms (+/- 36ms)
- with the patch: 652.5ms (+/- 22.9ms)
This commit addresses the issue by marking checksumming as unnecessary in
`unix_stream_sendmsg`
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Frederik Deweerdt <deweerdt.lkml@xxxxxxxxx>
Fixes: 2e910b95329c ("net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES")
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Joe Damato <jdamato@xxxxxxxxxx>
Link: https://patch.msgid.link/Z1fMaHkRf8cfubuE@xiberoa
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/unix/af_unix.c | 1 +
1 file changed, 1 insertion(+)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2313,6 +2313,7 @@ static int unix_stream_sendmsg(struct so
fds_sent = true;
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
err = skb_splice_from_iter(skb, &msg->msg_iter, size,
sk->sk_allocation);
if (err < 0) {
