MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2025-10-22 23:13:01 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

io_uring: ensure deferred completions are flushed for multishot

Browse Source 
Multishot normally uses io_req_post_cqe() to post completions, but when
stopping it, it may finish up with a deferred completion. This is fine,
except if another multishot event triggers before the deferred completions
get flushed. If this occurs, then CQEs may get reordered in the CQ ring,
as new multishot completions get posted before the deferred ones are
flushed. This can cause confusion on the application side, if strict
ordering is required for the use case.

When multishot posting via io_req_post_cqe(), flush any pending deferred
completions first, if any.

Cc: stable@vger.kernel.org # 6.1+
Reported-by: Norman Maurer <norman_maurer@apple.com>
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2025-05-07 07:34:24 -06:00
parent b53e523261
commit 687b2bae0e
1 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
io_uring/io_uring.c
View File

@ -848,6 +848,14 @@ bool io_req_post_cqe(struct io_kiocb *req, s32 res, u32 cflags)
struct io_ring_ctx *ctx = req->ctx;
bool posted;
/*
* If multishot has already posted deferred completions, ensure that
* those are flushed first before posting this one. If not, CQEs
* could get reordered.
*/
if (!wq_list_empty(&ctx->submit_state.compl_reqs))
__io_submit_flush_completions(ctx);
lockdep_assert(!io_wq_current_is_worker());
lockdep_assert_held(&ctx->uring_lock);