Subsystems providing external ubufs to the net layer, i.e. ->msg_ubuf,
might have a better way to refcount it. For instance, io_uring can
ammortise ref allocation.
Add a way to pass one extra ref to ->msg_ubuf into the network stack by
setting struct msghdr::msg_ubuf_ref bit. Whoever consumes the ref should
clear the flat. If not consumed, it's the responsibility of the caller
to put it. Make __ip{,6}_append_data() to use it.
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
include/linux/socket.h | 1 +
net/ipv4/ip_output.c | 3 +++
net/ipv6/ip6_output.c | 3 +++
3 files changed, 7 insertions(+)
diff --git a/include/linux/socket.h b/include/linux/socket.h
index ba84ee614d5a..ae869dee82de 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -72,6 +72,7 @@ struct msghdr {
* to be non-NULL.
*/
bool msg_managed_data : 1;
+ bool msg_ubuf_ref : 1;
unsigned int msg_flags; /* flags on received message */
__kernel_size_t msg_controllen; /* ancillary data buffer length */
struct kiocb *msg_iocb; /* ptr to iocb for async requests */
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 3fd1bf675598..d73ec0a73bd2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1032,6 +1032,9 @@ static int __ip_append_data(struct sock *sk,
paged = true;
zc = true;
uarg = msg->msg_ubuf;
+ /* we might've been given a free ref */
+ extra_uref = msg->msg_ubuf_ref;
+ msg->msg_ubuf_ref = false;
}
} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f4138ce6eda3..90bbaab21dbc 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1557,6 +1557,9 @@ static int __ip6_append_data(struct sock *sk,
paged = true;
zc = true;
uarg = msg->msg_ubuf;
+ /* we might've been given a free ref */
+ extra_uref = msg->msg_ubuf_ref;
+ msg->msg_ubuf_ref = false;
}
} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
--
2.36.1
