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io_uring: refactor poll arm error handling 

__io_arm_poll_handler() errors parsing is a horror, in case it failed it
returns 0 and the caller is expected to look at ipt.error, which already
led us to a number of problems before.

When it returns a valid mask, leave it as it's not, i.e. return 1 and
store the mask in ipt.result_mask. In case of a failure that can be
handled inline return an error code (negative value), and return 0 if
__io_arm_poll_handler() took ownership of the request and will complete
it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/018cacdaef5fe95d7dc56b32e85d752cab7607f6.1655990418.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-06-23 14:24:48 +01:00 committed by Jens Axboe
parent 063a007996
commit de08356f48
1 changed files with 21 additions and 23 deletions
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44
io_uring/poll.c
View File

@ -435,6 +435,12 @@ static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
(struct io_poll **) &pt->req->async_data);
}
/*
* Returns 0 when it's handed over for polling. The caller owns the requests if
* it returns non-zero, but otherwise should not touch it. Negative values
* contain an error code. When the result is >0, the polling has completed
* inline and ipt.result_mask is set to the mask.
*/
static int __io_arm_poll_handler(struct io_kiocb *req,
struct io_poll *poll,
struct io_poll_table *ipt, __poll_t mask)
@ -461,6 +467,17 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
atomic_set(&req->poll_refs, 1);
mask = vfs_poll(req->file, &ipt->pt) & poll->events;
if (unlikely(ipt->error || !ipt->nr_entries)) {
io_poll_remove_entries(req);
if (mask && (poll->events & EPOLLET)) {
ipt->result_mask = mask;
return 1;
} else {
return ipt->error ?: -EINVAL;
}
}
if (mask &&
((poll->events & (EPOLLET|EPOLLONESHOT)) == (EPOLLET|EPOLLONESHOT))) {
io_poll_remove_entries(req);
@ -469,25 +486,12 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
return 1;
}
if (!mask && unlikely(ipt->error || !ipt->nr_entries)) {
io_poll_remove_entries(req);
if (!ipt->error)
ipt->error = -EINVAL;
return 0;
}
if (req->flags & REQ_F_HASH_LOCKED)
io_poll_req_insert_locked(req);
else
io_poll_req_insert(req);
if (mask && (poll->events & EPOLLET)) {
/* can't multishot if failed, just queue the event we've got */
if (unlikely(ipt->error || !ipt->nr_entries)) {
poll->events |= EPOLLONESHOT;
req->apoll_events |= EPOLLONESHOT;
ipt->error = 0;
}
__io_poll_execute(req, mask);
return 0;
}
@ -582,9 +586,8 @@ int io_arm_poll_handler(struct io_kiocb *req, unsigned issue_flags)
io_kbuf_recycle(req, issue_flags);
ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask);
if (ret || ipt.error)
return ret ? IO_APOLL_READY : IO_APOLL_ABORTED;
if (ret)
return ret > 0 ? IO_APOLL_READY : IO_APOLL_ABORTED;
trace_io_uring_poll_arm(req, mask, apoll->poll.events);
return IO_APOLL_OK;
}
@ -815,16 +818,11 @@ int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
req->flags &= ~REQ_F_HASH_LOCKED;
ret = __io_arm_poll_handler(req, poll, &ipt, poll->events);
if (ret) {
if (ret > 0) {
io_req_set_res(req, ipt.result_mask, 0);
return IOU_OK;
}
if (ipt.error) {
req_set_fail(req);
return ipt.error;
}
return IOU_ISSUE_SKIP_COMPLETE;
return ret ?: IOU_ISSUE_SKIP_COMPLETE;
}
int io_poll_remove(struct io_kiocb *req, unsigned int issue_flags)