[PATCH v21 12/24] skb: implement skb_send_sock_locked_with_flags()

[Antonio Quartulli <antonio@openvpn.net>]

When sending an skb over a socket using skb_send_sock_locked(),
it is currently not possible to specify any flag to be set in
msghdr->msg_flags.

However, we may want to pass flags the user may have specified,
like MSG_NOSIGNAL.

Extend __skb_send_sock() with a new argument 'flags' and add a
new interface named skb_send_sock_locked_with_flags().

Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 include/linux/skbuff.h |  2 ++
 net/core/skbuff.c      | 18 +++++++++++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 14517e95a46c4e6f9a04ef7c7193b82b5e145b28..afd694b856b0dee3a657f23cb92cdd33885efbb1 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4162,6 +4162,8 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
 		    unsigned int flags);
 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
 			 int len);
+int skb_send_sock_locked_with_flags(struct sock *sk, struct sk_buff *skb,
+				    int offset, int len, int flags);
 int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len);
 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ab8acb737b93299f503e5c298b87e18edd59d555..bd627cfea8052faf3e9e745291b54ed22d2e7ed3 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3239,7 +3239,7 @@ static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg)
 
 typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg);
 static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
-			   int len, sendmsg_func sendmsg)
+			   int len, sendmsg_func sendmsg, int flags)
 {
 	unsigned int orig_len = len;
 	struct sk_buff *head = skb;
@@ -3257,7 +3257,7 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
 		kv.iov_base = skb->data + offset;
 		kv.iov_len = slen;
 		memset(&msg, 0, sizeof(msg));
-		msg.msg_flags = MSG_DONTWAIT;
+		msg.msg_flags = MSG_DONTWAIT | flags;
 
 		iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);
 		ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
@@ -3294,7 +3294,8 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
 		while (slen) {
 			struct bio_vec bvec;
 			struct msghdr msg = {
-				.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT,
+				.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT |
+					     flags,
 			};
 
 			bvec_set_page(&bvec, skb_frag_page(frag), slen,
@@ -3340,14 +3341,21 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
 			 int len)
 {
-	return __skb_send_sock(sk, skb, offset, len, sendmsg_locked);
+	return __skb_send_sock(sk, skb, offset, len, sendmsg_locked, 0);
 }
 EXPORT_SYMBOL_GPL(skb_send_sock_locked);
 
+int skb_send_sock_locked_with_flags(struct sock *sk, struct sk_buff *skb,
+				    int offset, int len, int flags)
+{
+	return __skb_send_sock(sk, skb, offset, len, sendmsg_locked, flags);
+}
+EXPORT_SYMBOL_GPL(skb_send_sock_locked_with_flags);
+
 /* Send skb data on a socket. Socket must be unlocked. */
 int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
 {
-	return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked);
+	return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked, 0);
 }
 
 /**

-- 
2.45.3