[PATCH v2 0/2] io_uring: fix CQE32 and CQE_MIXED ring refill handling

[Hui Peng <benquike@gmail.com>]

This series fixes two issues in io_cqe_cache_refill() and
io_fill_nop_cqe() for 32-byte CQEs:

1. Restrict skip CQE insertion at off + 1 == ctx->cq_entries to
   IORING_SETUP_CQE_MIXED rings so pure IORING_SETUP_CQE32 rings do not
   emit bogus IORING_CQE_F_SKIP entries.
2. Require 3 free CQ slots in io_fill_nop_cqe() before emitting a skip
   CQE for a 32-byte CQE wrapping across the end of an
   IORING_SETUP_CQE_MIXED ring, preventing an orphan skip CQE when fewer
   than 3 slots are free.

Changes in v2:
- Split into a 2-patch series and drop the third hunk from v1, as
  requested by Jens Axboe.

Hui Peng (2):
  io_uring: only insert skip CQE for IORING_SETUP_CQE_MIXED
  io_uring: require 3 free CQ slots for 32b CQE in io_fill_nop_cqe()

 io_uring/io_uring.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

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2.55.0.1082.g2b9226bbc0-goog