From: Eric Dumazet <edumazet@google.com>
Date: Fri, 6 Dec 2019 09:38:36 -0800
Subject: net: avoid an indirect call in ____sys_recvmsg()
Patch-mainline: v5.5-rc1
Git-commit: 1af66221a66de080274540a5c481ddacbe3574d2
References: bsc#1154353
CONFIG_RETPOLINE=y made indirect calls expensive.
gcc seems to add an indirect call in ____sys_recvmsg().
Rewriting the code slightly makes sure to avoid this indirection.
Alternative would be to not call sock_recvmsg() and instead
use security_socket_recvmsg() and sock_recvmsg_nosec(),
but this is less readable IMO.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: David Laight <David.Laight@aculab.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/socket.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/socket.c
+++ b/net/socket.c
@@ -2526,7 +2526,12 @@ static int ____sys_recvmsg(struct socket
if (sock->file->f_flags & O_NONBLOCK)
flags |= MSG_DONTWAIT;
- err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys, flags);
+
+ if (unlikely(nosec))
+ err = sock_recvmsg_nosec(sock, msg_sys, flags);
+ else
+ err = sock_recvmsg(sock, msg_sys, flags);
+
if (err < 0)
goto out;
len = err;