Commit b9557549 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/cmd: allow multishot polled commands 



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: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bcf97c31659662c72b69fc8fcdf2a88cfc16e430.1750065793.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 16215188

io_uring/uring_cmd.c

+23 −0
Original line number Diff line number Diff line
@@ -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;

}

io_uring/uring_cmd.h

+3 −0
Original line number Diff line number Diff line
@@ -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);