[PATCH 3/3] io_uring: use REQ_F_MULTI_CQES for multipoll IORING_OP_ADD

Hao Xu
2021-04-07T11:24:19Z

leverage REQ_F_MULTI_CQES to suppoort IORING_OP_ADD multishot.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
---
fs/io_uring.c | 13 ++++++++++---
include/uapi/linux/io_uring.h | 5 -----
2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index a7bd223ce2cc..952ad0ddb2db 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5361,20 +5361,27 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
{
struct io_poll_iocb *poll = &req->poll;
u32 events, flags;
+ bool multishot = req->flags & REQ_F_MULTI_CQES;
+ u32 update_bits = IORING_POLL_UPDATE_EVENTS |
+ IORING_POLL_UPDATE_USER_DATA;

if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (sqe->ioprio || sqe->buf_index)
return -EINVAL;
flags = READ_ONCE(sqe->len);
- if (flags & ~(IORING_POLL_ADD_MULTI | IORING_POLL_UPDATE_EVENTS |
- IORING_POLL_UPDATE_USER_DATA))
+ /*
+ * can't set REQ_F_MULTI_CQES with UPDATE flags, otherwise we count
+ * IO_POLL_ADD(IORING_POLL_UPDATE_*)'s cqe to ctx->cq_extra, which
+ * we shouldn't
+ */
+ if ((flags & ~update_bits) || (multishot && (flags & update_bits)))
return -EINVAL;
events = READ_ONCE(sqe->poll32_events);
#ifdef __BIG_ENDIAN
events = swahw32(events);
#endif
- if (!(flags & IORING_POLL_ADD_MULTI))
+ if (!multishot)
events |= EPOLLONESHOT;
poll->update_events = poll->update_user_data = false;
if (flags & IORING_POLL_UPDATE_EVENTS) {
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 303ac8005572..a3cd943b228e 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -166,14 +166,9 @@ enum {
* POLL_ADD flags. Note that since sqe->poll_events is the flag space, the
* command flags for POLL_ADD are stored in sqe->len.
*
- * 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_EVENTS (1U << 1)
#define IORING_POLL_UPDATE_USER_DATA (1U << 2)

--
1.8.3.1