[PATCH v5 3/5] io_uring/cmd: allow multishot polled commands
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2025-06-16 09:45:30
Also in:
io-uring
Subsystem:
io_uring, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Some commands like timestamping in the next patch can make use of multishot polling, i.e. REQ_F_APOLL_MULTISHOT. Add support for that, which is condensed in a single helper called io_cmd_poll_multishot(). The user who wants to continue with a request in a multishot mode must call the function, and only if it returns 0 the user is free to proceed. Apart from normal terminal errors, it can also end up with -EIOCBQUEUED, in which case the user must forward it to the core io_uring. It's forbidden to use task work while the request is executing in a multishot mode. The API is not foolproof, hence it's not exported to modules nor exposed in public headers. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- io_uring/uring_cmd.c | 23 +++++++++++++++++++++++ io_uring/uring_cmd.h | 3 +++ 2 files changed, 26 insertions(+)
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 9ad0ea5398c2..02cec6231831 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c@@ -12,6 +12,7 @@ #include "alloc_cache.h" #include "rsrc.h" #include "uring_cmd.h" +#include "poll.h" void io_cmd_cache_free(const void *entry) {
@@ -136,6 +137,9 @@ void __io_uring_cmd_do_in_task(struct io_uring_cmd *ioucmd, { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); + if (WARN_ON_ONCE(req->flags & REQ_F_APOLL_MULTISHOT)) + return; + ioucmd->task_work_cb = task_work_cb; req->io_task_work.func = io_uring_cmd_work; __io_req_task_work_add(req, flags);
@@ -158,6 +162,9 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, u64 res2, { struct io_kiocb *req = cmd_to_io_kiocb(ioucmd); + if (WARN_ON_ONCE(req->flags & REQ_F_APOLL_MULTISHOT)) + return; + io_uring_cmd_del_cancelable(ioucmd, issue_flags); if (ret < 0)
@@ -305,3 +312,19 @@ void io_uring_cmd_issue_blocking(struct io_uring_cmd *ioucmd) io_req_queue_iowq(req); } + +int io_cmd_poll_multishot(struct io_uring_cmd *cmd, + unsigned int issue_flags, __poll_t mask) +{ + struct io_kiocb *req = cmd_to_io_kiocb(cmd); + int ret; + + if (likely(req->flags & REQ_F_APOLL_MULTISHOT)) + return 0; + + req->flags |= REQ_F_APOLL_MULTISHOT; + mask &= ~EPOLLONESHOT; + + ret = io_arm_apoll(req, issue_flags, mask); + return ret == IO_APOLL_OK ? -EIOCBQUEUED : -ECANCELED; +}
diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
index a6dad47afc6b..50a6ccb831df 100644
--- a/io_uring/uring_cmd.h
+++ b/io_uring/uring_cmd.h@@ -18,3 +18,6 @@ bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx, struct io_uring_task *tctx, bool cancel_all); void io_cmd_cache_free(const void *entry); + +int io_cmd_poll_multishot(struct io_uring_cmd *cmd, + unsigned int issue_flags, __poll_t mask);
--
2.49.0