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net: Allow custom iter handler in msghdr

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Add support for custom iov_iter handling to msghdr. The idea is that
in-kernel subsystems want control over how an SG is split.

Signed-off-by: David Ahern <dsahern@kernel.org>
[pavel: move callback into msghdr]
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Ahern 2022-07-12 21:52:30 +01:00 committed by Jakub Kicinski
parent 7c701d92b2
commit ebe73a284f
4 changed files with 19 additions and 8 deletions
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7
include/linux/skbuff.h
View File

@ -1776,13 +1776,14 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg, void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
bool success); bool success);
int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb, int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
struct iov_iter *from, size_t length); struct sk_buff *skb, struct iov_iter *from,
size_t length);
static inline int skb_zerocopy_iter_dgram(struct sk_buff *skb, static inline int skb_zerocopy_iter_dgram(struct sk_buff *skb,
struct msghdr *msg, int len) struct msghdr *msg, int len)
{ {
return __zerocopy_sg_from_iter(skb->sk, skb, &msg->msg_iter, len); return __zerocopy_sg_from_iter(msg, skb->sk, skb, &msg->msg_iter, len);
} }
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb, int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,

4
include/linux/socket.h
View File

@ -14,6 +14,8 @@ struct file;
struct pid; struct pid;
struct cred; struct cred;
struct socket; struct socket;
struct sock;
struct sk_buff;
#define __sockaddr_check_size(size) \ #define __sockaddr_check_size(size) \
BUILD_BUG_ON(((size) > sizeof(struct __kernel_sockaddr_storage))) BUILD_BUG_ON(((size) > sizeof(struct __kernel_sockaddr_storage)))
@ -70,6 +72,8 @@ struct msghdr {
__kernel_size_t msg_controllen; /* ancillary data buffer length */ __kernel_size_t msg_controllen; /* ancillary data buffer length */
struct kiocb *msg_iocb; /* ptr to iocb for async requests */ struct kiocb *msg_iocb; /* ptr to iocb for async requests */
struct ubuf_info *msg_ubuf; struct ubuf_info *msg_ubuf;
int (*sg_from_iter)(struct sock *sk, struct sk_buff *skb,
struct iov_iter *from, size_t length);
}; };
struct user_msghdr { struct user_msghdr {

14
net/core/datagram.c
View File

@ -613,10 +613,16 @@ fault:
} }
EXPORT_SYMBOL(skb_copy_datagram_from_iter); EXPORT_SYMBOL(skb_copy_datagram_from_iter);
int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb, int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
struct iov_iter *from, size_t length) struct sk_buff *skb, struct iov_iter *from,
size_t length)
{ {
int frag = skb_shinfo(skb)->nr_frags; int frag;
if (msg && msg->sg_from_iter)
return msg->sg_from_iter(sk, skb, from, length);
frag = skb_shinfo(skb)->nr_frags;
while (length && iov_iter_count(from)) { while (length && iov_iter_count(from)) {
struct page *pages[MAX_SKB_FRAGS]; struct page *pages[MAX_SKB_FRAGS];
@ -702,7 +708,7 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
if (skb_copy_datagram_from_iter(skb, 0, from, copy)) if (skb_copy_datagram_from_iter(skb, 0, from, copy))
return -EFAULT; return -EFAULT;
return __zerocopy_sg_from_iter(NULL, skb, from, ~0U); return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U);
} }
EXPORT_SYMBOL(zerocopy_sg_from_iter); EXPORT_SYMBOL(zerocopy_sg_from_iter);

2
net/core/skbuff.c
View File

@ -1358,7 +1358,7 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
if (orig_uarg && uarg != orig_uarg) if (orig_uarg && uarg != orig_uarg)
return -EEXIST; return -EEXIST;
err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len); err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) { if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
struct sock *save_sk = skb->sk; struct sock *save_sk = skb->sk;