This adds a new POLL_ADD flag, IORING_POLL_UPDATE. As with the other
POLL_ADD flag, this one is masked into sqe->len. If set, the POLL_ADD
will have the following behavior:
- sqe->addr must contain the the user_data of the poll request that
needs to be modified. This field is otherwise invalid for a POLL_ADD
command.
- sqe->poll_events must contain the new mask for the existing poll
request. There are no checks for whether these are identical or not,
if a matching poll request is found, then it is re-armed with the new
mask.
A POLL_ADD with the IORING_POLL_UPDATE flag set may complete with any
of the following results:
1) 0, which means that we successfully found the existing poll request
specified, and performed the re-arm procedure. Any error from that
re-arm will be exposed as a completion event for that original poll
request, not for the update request.
2) -ENOENT, if no existing poll request was found with the given
user_data.
3) -EALREADY, if the existing poll request was already in the process of
being removed/canceled/completing.
4) -EACCES, if an attempt was made to modify an internal poll request
(eg not one originally issued ass IORING_OP_POLL_ADD).
The usual -EINVAL cases apply as well, if any invalid fields are set
in the sqe for this command type.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/io_uring.c | 73 ++++++++++++++++++++++++++++++++---
include/uapi/linux/io_uring.h | 4 ++
2 files changed, 72 insertions(+), 5 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8ed363bd95aa..79a40364e041 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -467,10 +467,14 @@ struct io_ring_ctx {
*/
struct io_poll_iocb {
struct file *file;
- struct wait_queue_head *head;
+ union {
+ struct wait_queue_head *head;
+ u64 addr;
+ };
__poll_t events;
bool done;
bool canceled;
+ bool update;
struct wait_queue_entry wait;
};
@@ -5004,6 +5008,7 @@ static void io_init_poll_iocb(struct io_poll_iocb *poll, __poll_t events,
poll->head = NULL;
poll->done = false;
poll->canceled = false;
+ poll->update = false;
poll->events = events;
INIT_LIST_HEAD(&poll->wait.entry);
init_waitqueue_func_entry(&poll->wait, wake_func);
@@ -5382,24 +5387,32 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
- if (sqe->addr || sqe->ioprio || sqe->off || sqe->buf_index)
+ if (sqe->ioprio || sqe->off || sqe->buf_index)
return -EINVAL;
flags = READ_ONCE(sqe->len);
- if (flags & ~IORING_POLL_ADD_MULTI)
+ if (flags & ~(IORING_POLL_ADD_MULTI | IORING_POLL_UPDATE))
return -EINVAL;
events = READ_ONCE(sqe->poll32_events);
#ifdef __BIG_ENDIAN
events = swahw32(events);
#endif
- if (!flags)
+ if (!(flags & IORING_POLL_ADD_MULTI))
events |= EPOLLONESHOT;
+ if (flags & IORING_POLL_UPDATE) {
+ poll->update = true;
+ poll->addr = READ_ONCE(sqe->addr);
+ } else {
+ if (sqe->addr)
+ return -EINVAL;
+ poll->update = false;
+ }
poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP |
(events & (EPOLLEXCLUSIVE|EPOLLONESHOT));
return 0;
}
-static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
+static int __io_poll_add(struct io_kiocb *req)
{
struct io_poll_iocb *poll = &req->poll;
struct io_ring_ctx *ctx = req->ctx;
@@ -5425,6 +5438,56 @@ static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
return ipt.error;
}
+static int io_poll_update(struct io_kiocb *req)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_kiocb *preq;
+ int ret;
+
+ spin_lock_irq(&ctx->completion_lock);
+ preq = io_poll_find(ctx, req->poll.addr);
+ if (!preq) {
+ ret = -ENOENT;
+ goto err;
+ } else if (preq->opcode != IORING_OP_POLL_ADD) {
+ /* don't allow internal poll updates */
+ ret = -EACCES;
+ goto err;
+ }
+ if (!__io_poll_remove_one(preq, &preq->poll)) {
+ /* in process of completing/removal */
+ ret = -EALREADY;
+ goto err;
+ }
+ /* we now have a detached poll request. reissue. */
+ ret = 0;
+err:
+ spin_unlock_irq(&ctx->completion_lock);
+ if (ret < 0) {
+ req_set_fail_links(req);
+finish:
+ io_req_complete(req, ret);
+ return 0;
+ }
+ /* only mask one event flags, keep behavior flags */
+ preq->poll.events &= ~0xffff;
+ preq->poll.events |= req->poll.events & 0xffff;
+ ret = __io_poll_add(preq);
+ if (ret < 0) {
+ req_set_fail_links(preq);
+ io_req_complete(preq, ret);
+ }
+ ret = 0;
+ goto finish;
+}
+
+static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
+{
+ if (!req->poll.update)
+ return __io_poll_add(req);
+ return io_poll_update(req);
+}
+
static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
{
struct io_timeout_data *data = container_of(timer,
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 76c967621601..44fe7f80c851 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -166,8 +166,12 @@ enum {
* IORING_POLL_ADD_MULTI Multishot poll. Sets IORING_CQE_F_MORE if
* the poll handler will continue to report
* CQEs on behalf of the same SQE.
+ *
+ * IORING_POLL_UPDATE Update existing poll request, matching
+ * sqe->addr as the old user_data field.
*/
#define IORING_POLL_ADD_MULTI (1U << 0)
+#define IORING_POLL_UPDATE (1U << 1)
/*
* IO completion data structure (Completion Queue Entry)
--
2.31.0
