linux-kernel - [PATCH -next 14/22] net: socket: add do_sys_recvmmsg() helper; remove in-kernel call to syscall

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Date:   Fri, 16 Mar 2018 18:06:06 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: [PATCH -next 14/22] net: socket: add do_sys_recvmmsg() helper; remove in-kernel call to syscall

Using the net-internal helper do_sys_recvmmsg() allows us to avoid the
internal calls to the sys_getsockopt() syscall.

Cc: David S. Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 net/socket.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index a05289b1f863..72cdaaeccb85 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2445,9 +2445,9 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 	return datagrams;
 }
 
-SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg,
-		unsigned int, vlen, unsigned int, flags,
-		struct timespec __user *, timeout)
+static long do_sys_recvmmsg(int fd, struct mmsghdr __user *mmsg,
+			    unsigned int vlen, unsigned int flags,
+			    struct timespec __user *timeout)
 {
 	int datagrams;
 	struct timespec timeout_sys;
@@ -2470,6 +2470,13 @@ SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg,
 	return datagrams;
 }
 
+SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg,
+		unsigned int, vlen, unsigned int, flags,
+		struct timespec __user *, timeout)
+{
+	return do_sys_recvmmsg(fd, mmsg, vlen, flags, timeout);
+}
+
 #ifdef __ARCH_WANT_SYS_SOCKETCALL
 /* Argument list sizes for sys_socketcall */
 #define AL(x) ((x) * sizeof(unsigned long))
@@ -2582,8 +2589,8 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
 		err = sys_recvmsg(a0, (struct user_msghdr __user *)a1, a[2]);
 		break;
 	case SYS_RECVMMSG:
-		err = sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3],
-				   (struct timespec __user *)a[4]);
+		err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2],
+				      a[3], (struct timespec __user *)a[4]);
 		break;
 	case SYS_ACCEPT4:
 		err = __sys_accept4(a0, (struct sockaddr __user *)a1,
-- 
2.16.2