6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavel Begunkov <asml.silence@xxxxxxxxx> Commit e0e4ab52d17096d96c21a6805ccd424b283c3c6d upstream. We disallow DEFER_TASKRUN multishots from running by io-wq, which is checked by individual opcodes in the issue path. We can consolidate all it in io_wq_submit_work() at the same time moving the checks out of the hot path. Suggested-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> Link: https://lore.kernel.org/r/e492f0f11588bb5aa11d7d24e6f53b7c7628afdb.1709905727.git.asml.silence@xxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- io_uring/io_uring.c | 20 ++++++++++++++++++++ io_uring/net.c | 21 --------------------- io_uring/rw.c | 2 -- 3 files changed, 20 insertions(+), 23 deletions(-) --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -949,6 +949,8 @@ bool io_fill_cqe_req_aux(struct io_kiocb u64 user_data = req->cqe.user_data; struct io_uring_cqe *cqe; + lockdep_assert(!io_wq_current_is_worker()); + if (!defer) return __io_post_aux_cqe(ctx, user_data, res, cflags, false); @@ -1950,6 +1952,24 @@ fail: goto fail; } + /* + * If DEFER_TASKRUN is set, it's only allowed to post CQEs from the + * submitter task context. Final request completions are handed to the + * right context, however this is not the case of auxiliary CQEs, + * which is the main mean of operation for multishot requests. + * Don't allow any multishot execution from io-wq. It's more restrictive + * than necessary and also cleaner. + */ + if (req->flags & REQ_F_APOLL_MULTISHOT) { + err = -EBADFD; + if (!file_can_poll(req->file)) + goto fail; + err = -ECANCELED; + if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK) + goto fail; + return; + } + if (req->flags & REQ_F_FORCE_ASYNC) { bool opcode_poll = def->pollin || def->pollout; --- a/io_uring/net.c +++ b/io_uring/net.c @@ -78,19 +78,6 @@ struct io_sr_msg { */ #define MULTISHOT_MAX_RETRY 32 -static inline bool io_check_multishot(struct io_kiocb *req, - unsigned int issue_flags) -{ - /* - * When ->locked_cq is set we only allow to post CQEs from the original - * task context. Usual request completions will be handled in other - * generic paths but multipoll may decide to post extra cqes. - */ - return !(issue_flags & IO_URING_F_IOWQ) || - !(req->flags & REQ_F_APOLL_MULTISHOT) || - !req->ctx->task_complete; -} - int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { struct io_shutdown *shutdown = io_kiocb_to_cmd(req, struct io_shutdown); @@ -837,9 +824,6 @@ int io_recvmsg(struct io_kiocb *req, uns (sr->flags & IORING_RECVSEND_POLL_FIRST)) return io_setup_async_msg(req, kmsg, issue_flags); - if (!io_check_multishot(req, issue_flags)) - return io_setup_async_msg(req, kmsg, issue_flags); - retry_multishot: if (io_do_buffer_select(req)) { void __user *buf; @@ -935,9 +919,6 @@ int io_recv(struct io_kiocb *req, unsign (sr->flags & IORING_RECVSEND_POLL_FIRST)) return -EAGAIN; - if (!io_check_multishot(req, issue_flags)) - return -EAGAIN; - sock = sock_from_file(req->file); if (unlikely(!sock)) return -ENOTSOCK; @@ -1386,8 +1367,6 @@ int io_accept(struct io_kiocb *req, unsi struct file *file; int ret, fd; - if (!io_check_multishot(req, issue_flags)) - return -EAGAIN; retry: if (!fixed) { fd = __get_unused_fd_flags(accept->flags, accept->nofile); --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -932,8 +932,6 @@ int io_read_mshot(struct io_kiocb *req, */ if (!file_can_poll(req->file)) return -EBADFD; - if (issue_flags & IO_URING_F_IOWQ) - return -EAGAIN; ret = __io_read(req, issue_flags);
