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Sun, 23 Feb 2025 16:17:12 -0800 (PST) Message-ID: <9d8b1613-ed11-4313-9d47-a5fc357ba910@davidwei.uk> Date: Sun, 23 Feb 2025 16:17:12 -0800 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] io_uring/zcrx: add single shot recvzc Content-Language: en-GB To: lizetao Cc: Jens Axboe , Pavel Begunkov , "io-uring@vger.kernel.org" References: <20250221205146.1210952-1-dw@davidwei.uk> <20250221205146.1210952-2-dw@davidwei.uk> <28fef9180ec04610b601b15c06eb70c5@huawei.com> From: David Wei In-Reply-To: <28fef9180ec04610b601b15c06eb70c5@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2025-02-22 00:54, lizetao wrote: > Hi, > >> -----Original Message----- >> From: David Wei >> Sent: Saturday, February 22, 2025 4:52 AM >> To: io-uring@vger.kernel.org >> Cc: Jens Axboe ; Pavel Begunkov >> Subject: [PATCH v2 1/2] io_uring/zcrx: add single shot recvzc >> >> 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 >> --- >> io_uring/net.c | 19 +++++++++++++++++-- io_uring/zcrx.c | 17 ++++++++++++-- >> --- io_uring/zcrx.h | 2 +- >> 3 files changed, 30 insertions(+), 8 deletions(-) >> >> diff --git a/io_uring/net.c b/io_uring/net.c index 000dc70d08d0..cae34a24266c >> 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; >> struct io_zcrx_ifq *ifq; >> }; >> >> @@ -1241,7 +1242,7 @@ int io_recvzc_prep(struct io_kiocb *req, const struct >> io_uring_sqe *sqe) >> unsigned ifq_idx; >> >> if (unlikely(sqe->file_index || sqe->addr2 || sqe->addr || >> - sqe->len || sqe->addr3)) >> + sqe->addr3)) >> return -EINVAL; >> >> ifq_idx = READ_ONCE(sqe->zcrx_ifq_idx); @@ -1250,6 +1251,12 @@ >> 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; >> + /* UINT_MAX means no limit on readlen */ > > What is the difference between unlimited read length and IO_URING_F_MULTISHOT? > In what specific scenarios would unlimited read length be used? I will clean up the terminology in the next revision. There isn't a singleshot vs multishot as such. Rather, it's an unlimited multishot vs a limited multishot. The unlimited multishot request would be a typical multishot recv that will keep reading data from the socket. The limited multishot request will read up to a limit N before completing the request. > >> + if (!zc->len) >> + zc->len = UINT_MAX; >> >> zc->flags = READ_ONCE(sqe->ioprio); >> zc->msg_flags = READ_ONCE(sqe->msg_flags); @@ -1269,6 +1276,7 >> @@ int io_recvzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) >> int io_recvzc(struct io_kiocb *req, unsigned int issue_flags) { >> struct io_recvzc *zc = io_kiocb_to_cmd(req, struct io_recvzc); >> + bool limit = zc->len != UINT_MAX; > > It is not used. > >> struct socket *sock; >> int ret; >> >> @@ -1281,7 +1289,7 @@ 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 +1304,13 @@ int io_recvzc(struct io_kiocb *req, unsigned int >> issue_flags) >> return IOU_OK; >> } >> >> + if (zc->len == 0) { >> + io_req_set_res(req, 0, 0); >> + >> + if (issue_flags & IO_URING_F_MULTISHOT) >> + return IOU_STOP_MULTISHOT; >> + 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 >> f2d326e18e67..74bca4e471bc 100644 >> --- a/io_uring/zcrx.c >> +++ b/io_uring/zcrx.c >> @@ -817,6 +817,7 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct >> sk_buff *skb, >> int i, copy, end, off; >> int ret = 0; >> >> + len = min_t(size_t, len, desc->count); >> if (unlikely(args->nr_skbs++ > IO_SKBS_PER_CALL_LIMIT)) >> return -EAGAIN; >> >> @@ -894,26 +895,32 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct >> sk_buff *skb, >> out: >> if (offset == start_off) >> return ret; >> + if (desc->count != UINT_MAX) >> + desc->count -= (offset - start_off); >> 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 int *outlen) >> { >> + unsigned int len = *outlen; >> + bool limit = len != UINT_MAX; >> struct io_zcrx_args args = { >> .req = req, >> .ifq = ifq, >> .sock = sk->sk_socket, >> }; >> read_descriptor_t rd_desc = { >> - .count = 1, >> + .count = len, >> .arg.data = &args, >> }; >> int ret; >> >> lock_sock(sk); >> ret = tcp_read_sock(sk, &rd_desc, io_zcrx_recv_skb); >> + if (limit && ret) >> + *outlen = len - ret; >> if (ret <= 0) { >> if (ret < 0 || sock_flag(sk, SOCK_DONE)) >> goto out; >> @@ -930,7 +937,7 @@ 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 (issue_flags & IO_URING_F_MULTISHOT) >> + if (!limit && (issue_flags & IO_URING_F_MULTISHOT)) >> ret = IOU_REQUEUE; >> else >> ret = -EAGAIN; >> @@ -942,7 +949,7 @@ static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, >> struct io_zcrx_ifq *ifq, >> >> int io_zcrx_recv(struct io_kiocb *req, struct io_zcrx_ifq *ifq, >> struct socket *sock, unsigned int flags, >> - unsigned issue_flags) >> + unsigned issue_flags, unsigned int *len) >> { >> struct sock *sk = sock->sk; >> const struct proto *prot = READ_ONCE(sk->sk_prot); @@ -951,5 >> +958,5 @@ int io_zcrx_recv(struct io_kiocb *req, struct io_zcrx_ifq *ifq, >> return -EPROTONOSUPPORT; >> >> sock_rps_record_flow(sk); >> - return io_zcrx_tcp_recvmsg(req, ifq, sk, flags, issue_flags); >> + return io_zcrx_tcp_recvmsg(req, ifq, sk, flags, issue_flags, len); >> } >> diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h index >> a16bdd921f03..1b4042dc48e2 100644 >> --- a/io_uring/zcrx.h >> +++ b/io_uring/zcrx.h >> @@ -46,7 +46,7 @@ void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx); void >> io_shutdown_zcrx_ifqs(struct io_ring_ctx *ctx); int io_zcrx_recv(struct io_kiocb >> *req, struct io_zcrx_ifq *ifq, >> struct socket *sock, unsigned int flags, >> - unsigned issue_flags); >> + unsigned issue_flags, unsigned int *len); >> #else >> static inline int io_register_zcrx_ifq(struct io_ring_ctx *ctx, >> struct io_uring_zcrx_ifq_reg __user >> *arg) >> -- >> 2.43.5 >> >> > > --- > Li Zetao