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authorPavel Begunkov <asml.silence@gmail.com>2023-01-04 01:34:02 +0000
committerJens Axboe <axboe@kernel.dk>2023-01-03 19:03:28 -0700
commit9ffa13ff78a0a55df968a72d6f0ebffccee5c9f4 (patch)
tree3576e12a99775bf257075621191860613552fd4b
parentaf82425c6a2d2f347c79b63ce74fca6dc6be157f (diff)
downloadlinux-next-9ffa13ff78a0a55df968a72d6f0ebffccee5c9f4.tar.gz
io_uring: pin context while queueing deferred tw
Unlike normal tw, nothing prevents deferred tw to be executed right after an tw item added to ->work_llist in io_req_local_work_add(). For instance, the waiting task may get waken up by CQ posting or a normal tw. Thus we need to pin the ring for the rest of io_req_local_work_add() Cc: stable@vger.kernel.org Fixes: c0e0d6ba25f18 ("io_uring: add IORING_SETUP_DEFER_TASKRUN") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1a79362b9c10b8523ef70b061d96523650a23344.1672795998.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--io_uring/io_uring.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 58ac13b69dc8..6bed44855679 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1236,13 +1236,18 @@ static void io_req_local_work_add(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
- if (!llist_add(&req->io_task_work.node, &ctx->work_llist))
+ percpu_ref_get(&ctx->refs);
+
+ if (!llist_add(&req->io_task_work.node, &ctx->work_llist)) {
+ percpu_ref_put(&ctx->refs);
return;
+ }
/* need it for the following io_cqring_wake() */
smp_mb__after_atomic();
if (unlikely(atomic_read(&req->task->io_uring->in_idle))) {
io_move_task_work_from_local(ctx);
+ percpu_ref_put(&ctx->refs);
return;
}
@@ -1252,6 +1257,7 @@ static void io_req_local_work_add(struct io_kiocb *req)
if (ctx->has_evfd)
io_eventfd_signal(ctx);
__io_cqring_wake(ctx);
+ percpu_ref_put(&ctx->refs);
}
void __io_req_task_work_add(struct io_kiocb *req, bool allow_local)