6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jens Axboe axboe@kernel.dk
[ Upstream commit 7c71a0af81ba72de9b2c501065e4e718aba9a271 ]
Current recv bundles are only supported for multishot receives, and additionally they also always post at least 2 CQEs if more data is available than what a buffer will hold. This happens because the initial bundle recv will do a single buffer, and then do the rest of what is in the socket as a followup receive. As shown in a test program, if 1k buffers are available and 32k is available to receive in the socket, you'd get the following completions:
bundle=1, mshot=0 cqe res 1024 cqe res 1024 [...] cqe res 1024
bundle=1, mshot=1 cqe res 1024 cqe res 31744
where bundle=1 && mshot=0 will post 32 1k completions, and bundle=1 && mshot=1 will post a 1k completion and then a 31k completion.
To support bundle recv without multishot, it's possible to simply retry the recv immediately and post a single completion, rather than split it into two completions. With the below patch, the same test looks as follows:
bundle=1, mshot=0 cqe res 32768
bundle=1, mshot=1 cqe res 32768
where mshot=0 works fine for bundles, and both of them post just a single 32k completion rather than split it into separate completions. Posting fewer completions is always a nice win, and not needing multishot for proper bundle efficiency is nice for cases that can't necessarily use multishot.
Reported-by: Norman Maurer norman_maurer@apple.com Link: https://lore.kernel.org/r/184f9f92-a682-4205-a15d-89e18f664502@kernel.dk Fixes: 2f9c9515bdfd ("io_uring/net: support bundles for recv") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- io_uring/net.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/io_uring/net.c b/io_uring/net.c index f4c626029ba7b..bfdbbf0b9e90d 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -76,6 +76,7 @@ struct io_sr_msg { /* initialised and used only by !msg send variants */ u16 buf_group; u16 buf_index; + bool retry; void __user *msg_control; /* used only for send zerocopy */ struct io_kiocb *notif; @@ -202,6 +203,7 @@ static inline void io_mshot_prep_retry(struct io_kiocb *req,
req->flags &= ~REQ_F_BL_EMPTY; sr->done_io = 0; + sr->retry = false; sr->len = 0; /* get from the provided buffer */ req->buf_index = sr->buf_group; } @@ -416,6 +418,7 @@ int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
sr->done_io = 0; + sr->retry = false;
if (req->opcode != IORING_OP_SEND) { if (sqe->addr2 || sqe->file_index) @@ -785,6 +788,7 @@ int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
sr->done_io = 0; + sr->retry = false;
if (unlikely(sqe->file_index || sqe->addr2)) return -EINVAL; @@ -833,6 +837,9 @@ int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return io_recvmsg_prep_setup(req); }
+/* bits to clear in old and inherit in new cflags on bundle retry */ +#define CQE_F_MASK (IORING_CQE_F_SOCK_NONEMPTY|IORING_CQE_F_MORE) + /* * Finishes io_recv and io_recvmsg. * @@ -852,9 +859,19 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret, if (sr->flags & IORING_RECVSEND_BUNDLE) { cflags |= io_put_kbufs(req, *ret, io_bundle_nbufs(kmsg, *ret), issue_flags); + if (sr->retry) + cflags = req->cqe.flags | (cflags & CQE_F_MASK); /* bundle with no more immediate buffers, we're done */ if (req->flags & REQ_F_BL_EMPTY) goto finish; + /* if more is available, retry and append to this one */ + if (!sr->retry && kmsg->msg.msg_inq > 0 && *ret > 0) { + req->cqe.flags = cflags & ~CQE_F_MASK; + sr->len = kmsg->msg.msg_inq; + sr->done_io += *ret; + sr->retry = true; + return false; + } } else { cflags |= io_put_kbuf(req, *ret, issue_flags); } @@ -1233,6 +1250,7 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) struct io_kiocb *notif;
zc->done_io = 0; + zc->retry = false; req->flags |= REQ_F_POLL_NO_LAZY;
if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))