Commit d4e7cd36 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: sanitize double poll handling

There's a bit of confusion on the matching pairs of poll vs double poll,
depending on if the request is a pure poll (IORING_OP_POLL_ADD) or
poll driven retry.

Add io_poll_get_double() that returns the double poll waitqueue, if any,
and io_poll_get_single() that returns the original poll waitqueue. With
that, remove the argument to io_poll_remove_double().

Finally ensure that wait->private is cleared once the double poll handler
has run, so that remove knows it's already been seen.

Cc: # v5.8
Fixes: 18bceab1

 ("io_uring: allow POLL_ADD with double poll_wait() users")
Signed-off-by: default avatarJens Axboe <>
parent 227c0c96
......@@ -4649,9 +4649,24 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
return false;
static void io_poll_remove_double(struct io_kiocb *req, void *data)
static struct io_poll_iocb *io_poll_get_double(struct io_kiocb *req)
struct io_poll_iocb *poll = data;
/* pure poll stashes this in ->io, poll driven retry elsewhere */
if (req->opcode == IORING_OP_POLL_ADD)
return (struct io_poll_iocb *) req->io;
return req->apoll->double_poll;
static struct io_poll_iocb *io_poll_get_single(struct io_kiocb *req)
if (req->opcode == IORING_OP_POLL_ADD)
return &req->poll;
return &req->apoll->poll;
static void io_poll_remove_double(struct io_kiocb *req)
struct io_poll_iocb *poll = io_poll_get_double(req);
......@@ -4671,7 +4686,7 @@ static void io_poll_complete(struct io_kiocb *req, __poll_t mask, int error)
struct io_ring_ctx *ctx = req->ctx;
io_poll_remove_double(req, req->io);
req->poll.done = true;
io_cqring_fill_event(req, error ? error : mangle_poll(mask));
......@@ -4711,7 +4726,7 @@ static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode,
int sync, void *key)
struct io_kiocb *req = wait->private;
struct io_poll_iocb *poll = req->apoll->double_poll;
struct io_poll_iocb *poll = io_poll_get_single(req);
__poll_t mask = key_to_poll(key);
/* for instances that support it check for an event match first: */
......@@ -4725,6 +4740,8 @@ static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode,
done = list_empty(&poll->wait.entry);
if (!done)
/* make sure double remove sees this as being gone */
wait->private = NULL;
if (!done)
__io_async_wake(req, poll, mask, io_poll_task_func);
......@@ -4808,7 +4825,7 @@ static void io_async_task_func(struct callback_head *cb)
if (hash_hashed(&req->hash_node))
io_poll_remove_double(req, apoll->double_poll);
if (!READ_ONCE(apoll->poll.canceled))
......@@ -4919,7 +4936,7 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask,
if (ret || ipt.error) {
io_poll_remove_double(req, apoll->double_poll);
......@@ -4951,14 +4968,13 @@ static bool io_poll_remove_one(struct io_kiocb *req)
bool do_complete;
if (req->opcode == IORING_OP_POLL_ADD) {
io_poll_remove_double(req, req->io);
do_complete = __io_poll_remove_one(req, &req->poll);
} else {
struct async_poll *apoll = req->apoll;
io_poll_remove_double(req, apoll->double_poll);
/* non-poll requests have submit ref still */
do_complete = __io_poll_remove_one(req, &apoll->poll);
if (do_complete) {
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