On 2/18/25 16:57, David Wei wrote:
Currently only multishot recvzc requests are supported, but sometimes
there is a need to do a single recv e.g. peeking at some data in the
socket. Add single shot recvzc requests where IORING_RECV_MULTISHOT is
_not_ set and the sqe->len field is set to the number of bytes to read
N.
There could be multiple completions containing data, like the multishot
case, since N bytes could be split across multiple frags. This is
followed by a final completion with res and cflags both set to 0 that
indicate the completion of the request, or a -res that indicate an
error.
Signed-off-by: David Wei <dw@xxxxxxxxxxx>
---
io_uring/net.c | 26 ++++++++++++++++++--------
io_uring/zcrx.c | 17 ++++++++++++++---
io_uring/zcrx.h | 2 +-
3 files changed, 33 insertions(+), 12 deletions(-)
diff --git a/io_uring/net.c b/io_uring/net.c
index 000dc70d08d0..d3a9aaa52a13 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -94,6 +94,7 @@ struct io_recvzc {
struct file *file;
unsigned msg_flags;
u16 flags;
+ u32 len;
Something is up with the types, it's u32, for which you use
UINT_MAX, and later convert to ulong.
struct io_zcrx_ifq *ifq;
};
...
@@ -1250,6 +1251,9 @@ int io_recvzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
zc->ifq = req->ctx->ifq;
if (!zc->ifq)
return -EINVAL;
+ zc->len = READ_ONCE(sqe->len);
+ if (zc->len == UINT_MAX)
+ return -EINVAL;
zc->flags = READ_ONCE(sqe->ioprio);
zc->msg_flags = READ_ONCE(sqe->msg_flags);
@@ -1257,12 +1261,14 @@ int io_recvzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
return -EINVAL;
if (zc->flags & ~(IORING_RECVSEND_POLL_FIRST | IORING_RECV_MULTISHOT))
return -EINVAL;
- /* multishot required */
- if (!(zc->flags & IORING_RECV_MULTISHOT))
- return -EINVAL;
- /* All data completions are posted as aux CQEs. */
- req->flags |= REQ_F_APOLL_MULTISHOT;
-
+ if (zc->flags & IORING_RECV_MULTISHOT) {
+ if (zc->len)
+ return -EINVAL;
+ /* All data completions are posted as aux CQEs. */
+ req->flags |= REQ_F_APOLL_MULTISHOT;
If you're posting "aux" cqes you have to set the flag for
synchronisation reasons. We probably can split out a "I want to post
aux cqes" flag, but it seems like you don't actually care about
multishot here but limiting the length, or limiting the length + nowait.
+ }
+ if (!zc->len)
+ zc->len = UINT_MAX;
return 0;
}
@@ -1281,7 +1287,7 @@ int io_recvzc(struct io_kiocb *req, unsigned int issue_flags)
return -ENOTSOCK;
ret = io_zcrx_recv(req, zc->ifq, sock, zc->msg_flags | MSG_DONTWAIT,
- issue_flags);
+ issue_flags, zc->len);
if (unlikely(ret <= 0) && ret != -EAGAIN) {
if (ret == -ERESTARTSYS)
ret = -EINTR;
@@ -1296,6 +1302,10 @@ int io_recvzc(struct io_kiocb *req, unsigned int issue_flags)
return IOU_OK;
}
+ if (zc->len != UINT_MAX) {
+ io_req_set_res(req, ret, 0);
+ return IOU_OK;
+ }
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_ISSUE_SKIP_COMPLETE;
return -EAGAIN;
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index ea099f746599..834c887743c8 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -106,6 +106,7 @@ struct io_zcrx_args {
struct io_zcrx_ifq *ifq;
struct socket *sock;
unsigned nr_skbs;
+ unsigned long len;
};
static const struct memory_provider_ops io_uring_pp_zc_ops;
@@ -826,6 +827,10 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
int i, copy, end, off;
int ret = 0;
+ if (args->len == 0)
+ return -EINTR;
+ len = (args->len != UINT_MAX) ? min_t(size_t, len, args->len) : len;
Just min?
+
if (unlikely(args->nr_skbs++ > IO_SKBS_PER_CALL_LIMIT))
return -EAGAIN;
@@ -920,17 +925,21 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
out:
if (offset == start_off)
return ret;
+ args->len -= (offset - start_off);
Doesn't it unconditionally change the magic value UINT_MAX
you're trying to preserve?
+ if (args->len == 0)
+ desc->count = 0;
return offset - start_off;
}
static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
struct sock *sk, int flags,
- unsigned issue_flags)
+ unsigned issue_flags, unsigned long len)
{
struct io_zcrx_args args = {
.req = req,
.ifq = ifq,
.sock = sk->sk_socket,
+ .len = len,
};
read_descriptor_t rd_desc = {
.count = 1,
@@ -956,6 +965,8 @@ static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
ret = IOU_REQUEUE;
} else if (sock_flag(sk, SOCK_DONE)) {
/* Make it to retry until it finally gets 0. */
+ if (len != UINT_MAX)
+ goto out;
if (issue_flags & IO_URING_F_MULTISHOT)
ret = IOU_REQUEUE;
else
--
Pavel Begunkov
