On 6/21/22 13:25, Pavel Begunkov wrote:
apoll_events should be set once in the beginning of poll arming just as
poll->events and not change after. However, currently io_uring resets it
on each __io_poll_execute() for no clear reason. There is also a place
in __io_arm_poll_handler() where we add EPOLLONESHOT to downgrade a
multishot, but forget to do the same thing with ->apoll_events, which is
buggy.
Fixes: 81459350d581e ("io_uring: cache req->apoll->events in req->cflags")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
fs/io_uring.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 87c65a358678..ebda9a565fc0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6954,7 +6954,8 @@ static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
io_req_complete_failed(req, ret);
}
-static void __io_poll_execute(struct io_kiocb *req, int mask, __poll_t events)
+static void __io_poll_execute(struct io_kiocb *req, int mask,
+ __poll_t __maybe_unused events)
Killing @events would add extra rebase conflicts, so left it here and will
send a clean up for 5.20.
{
req->cqe.res = mask;
/*
@@ -6963,7 +6964,6 @@ static void __io_poll_execute(struct io_kiocb *req, int mask, __poll_t events)
* CPU. We want to avoid pulling in req->apoll->events for that
* case.
*/
- req->apoll_events = events;
if (req->opcode == IORING_OP_POLL_ADD)
req->io_task_work.func = io_poll_task_func;
else
@@ -7114,6 +7114,8 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
io_init_poll_iocb(poll, mask, io_poll_wake);
poll->file = req->file;
+ req->apoll_events = poll->events;
+
ipt->pt._key = mask;
ipt->req = req;
ipt->error = 0;
@@ -7144,8 +7146,10 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
if (mask) {
/* can't multishot if failed, just queue the event we've got */
- if (unlikely(ipt->error || !ipt->nr_entries))
+ if (unlikely(ipt->error || !ipt->nr_entries)) {
poll->events |= EPOLLONESHOT;
+ req->apoll_events |= EPOLLONESHOT;
+ }
__io_poll_execute(req, mask, poll->events);
return 0;
}
@@ -7392,7 +7396,7 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
return -EINVAL;
io_req_set_refcount(req);
- req->apoll_events = poll->events = io_poll_parse_events(sqe, flags);
+ poll->events = io_poll_parse_events(sqe, flags);
return 0;
}
--
Pavel Begunkov
