Messages in this thread | | | Date | Sat, 7 May 2022 17:13:10 +0800 | Subject | Re: [PATCH 5/5] io_uring: implement multishot mode for accept | From | Hao Xu <> |
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在 2022/5/6 下午10:42, Jens Axboe 写道: > On 5/6/22 1:01 AM, Hao Xu wrote: >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 0a83ecc457d1..9febe7774dc3 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -1254,6 +1254,7 @@ static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags); >> static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer); >> static void io_eventfd_signal(struct io_ring_ctx *ctx); >> static void io_req_tw_post_queue(struct io_kiocb *req, s32 res, u32 cflags); >> +static void io_poll_remove_entries(struct io_kiocb *req); >> >> static struct kmem_cache *req_cachep; >> >> @@ -5690,24 +5691,29 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags) >> static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) >> { >> struct io_accept *accept = &req->accept; >> + bool multishot; >> >> if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL)) >> return -EINVAL; >> - if (sqe->ioprio || sqe->len || sqe->buf_index) >> + if (sqe->len || sqe->buf_index) >> return -EINVAL; >> >> accept->addr = u64_to_user_ptr(READ_ONCE(sqe->addr)); >> accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2)); >> accept->flags = READ_ONCE(sqe->accept_flags); >> accept->nofile = rlimit(RLIMIT_NOFILE); >> + multishot = !!(READ_ONCE(sqe->ioprio) & IORING_ACCEPT_MULTISHOT); > > I tend to like: > > multishot = READ_ONCE(sqe->ioprio) & IORING_ACCEPT_MULTISHOT) != 0; > > as I think it's more readable. But I think we really want it ala: > > u16 poll_flags; > > poll_flags = READ_ONCE(sqe->ioprio); > if (poll_flags & ~IORING_ACCEPT_MULTISHOT) > return -EINVAL; > > ... > > to ensure that we can add more flags later, hence only accepting this > single flag right now. > > Do we need REQ_F_APOLL_MULTI_POLLED, or can we just store whether this > is a multishot request in struct io_accept? I think we can do it in this way, but it may be a bit inconvenient if we add other multishot OPCODE. With REQ_F_APOLL_MULTI_POLLED we can just check req->flags in the poll arming path, which keeps it op unrelated. > >> @@ -5760,7 +5774,35 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags) >> ret = io_install_fixed_file(req, file, issue_flags, >> accept->file_slot - 1); >> } >> - __io_req_complete(req, issue_flags, ret, 0); >> + >> + if (req->flags & REQ_F_APOLL_MULTISHOT) { >> + if (ret >= 0) { >> + bool filled; >> + >> + spin_lock(&ctx->completion_lock); >> + filled = io_fill_cqe_aux(ctx, req->cqe.user_data, ret, >> + IORING_CQE_F_MORE); >> + io_commit_cqring(ctx); >> + spin_unlock(&ctx->completion_lock); >> + if (unlikely(!filled)) { >> + io_poll_clean(req); >> + return -ECANCELED; >> + } >> + io_cqring_ev_posted(ctx); >> + goto retry; >> + } else { >> + /* >> + * the apoll multishot req should handle poll >> + * cancellation by itself since the upper layer >> + * who called io_queue_sqe() cannot get errors >> + * happened here. >> + */ >> + io_poll_clean(req); >> + return ret; >> + } >> + } else { >> + __io_req_complete(req, issue_flags, ret, 0); >> + } >> return 0; >> } > > I'd probably just make that: > > if (!(req->flags & REQ_F_APOLL_MULTISHOT)) { > __io_req_complete(req, issue_flags, ret, 0); > return 0; > } > if (ret >= 0) { > bool filled; > > spin_lock(&ctx->completion_lock); > filled = io_fill_cqe_aux(ctx, req->cqe.user_data, ret, > IORING_CQE_F_MORE); > io_commit_cqring(ctx); > spin_unlock(&ctx->completion_lock); > if (filled) { > io_cqring_ev_posted(ctx); > goto retry; > } > /* fall through to error case */ > ret = -ECANCELED; > } > > /* > * the apoll multishot req should handle poll > * cancellation by itself since the upper layer > * who called io_queue_sqe() cannot get errors > * happened here. > */ > io_poll_clean(req); > return ret; > > which I think is a lot easier to read and keeps the indentation at a > manageable level and reduces duplicate code. Great, thanks, it's better. >
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