Commit 0739cd28 authored by Cong Wang's avatar Cong Wang Committed by Alexei Starovoitov
Browse files

net: Introduce skb_send_sock() for sock_map 



We only have skb_send_sock_locked() which requires callers
to use lock_sock(). Introduce a variant skb_send_sock()
which locks on its own, callers do not need to lock it
any more. This will save us from adding a ->sendmsg_locked
for each protocol.

To reuse the code, pass function pointers to __skb_send_sock()
and build skb_send_sock() and skb_send_sock_locked() on top.

Signed-off-by: default avatarCong Wang <cong.wang@bytedance.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-4-xiyou.wangcong@gmail.com
parent b01fd6e8

include/linux/skbuff.h

+1 −0
Original line number Diff line number Diff line
@@ -3626,6 +3626,7 @@ 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(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);

int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,

net/core/skbuff.c

+48 −7
Original line number Diff line number Diff line
@@ -2500,9 +2500,32 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset, 
}

EXPORT_SYMBOL_GPL(skb_splice_bits);



/* Send skb data on a socket. Socket must be locked. */

int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,

			 int len)

static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,

			    struct kvec *vec, size_t num, size_t size)

{

	struct socket *sock = sk->sk_socket;



	if (!sock)

		return -EINVAL;

	return kernel_sendmsg(sock, msg, vec, num, size);

}



static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,

			     size_t size, int flags)

{

	struct socket *sock = sk->sk_socket;



	if (!sock)

		return -EINVAL;

	return kernel_sendpage(sock, page, offset, size, flags);

}



typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,

			    struct kvec *vec, size_t num, size_t size);

typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,

			     size_t size, int flags);

static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,

			   int len, sendmsg_func sendmsg, sendpage_func sendpage)

{

	unsigned int orig_len = len;

	struct sk_buff *head = skb;
@@ -2522,7 +2545,8 @@ int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset, 
		memset(&msg, 0, sizeof(msg));

		msg.msg_flags = MSG_DONTWAIT;



		ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);

		ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,

				      sendmsg_unlocked, sk, &msg, &kv, 1, slen);

		if (ret <= 0)

			goto error;
@@ -2553,7 +2577,9 @@ int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset, 
		slen = min_t(size_t, len, skb_frag_size(frag) - offset);



		while (slen) {

			ret = kernel_sendpage_locked(sk, skb_frag_page(frag),

			ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,

					      sendpage_unlocked, sk,

					      skb_frag_page(frag),

					      skb_frag_off(frag) + offset,

					      slen, MSG_DONTWAIT);

			if (ret <= 0)
@@ -2587,8 +2613,23 @@ int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset, 
error:

	return orig_len == len ? ret : orig_len - len;

}



/* Send skb data on a socket. Socket must be locked. */

int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,

			 int len)

{

	return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,

			       kernel_sendpage_locked);

}

EXPORT_SYMBOL_GPL(skb_send_sock_locked);



/* 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,

			       sendpage_unlocked);

}



/**

 *	skb_store_bits - store bits from kernel buffer to skb

 *	@skb: destination buffer