io_uring: add io_add_aux_cqe() helper

This helper will post a CQE, and can be called from task_work where we
now that the ctx is already properly locked and that deferred
completions will get flushed later on.

Signed-off-by: Jens Axboe <[email protected]>

Author: axboe

io_uring/io_uring.c

@@ -801,19 +801,38 @@ static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res,
 	return false;
 }
 
-bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
+static bool __io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res,
+			      u32 cflags)
 {
 	bool filled;
 
-	io_cq_lock(ctx);
 	filled = io_fill_cqe_aux(ctx, user_data, res, cflags);
 	if (!filled)
 		filled = io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
 
+	return filled;
+}
+
+bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
+{
+	bool filled;
+
+	io_cq_lock(ctx);
+	filled = __io_post_aux_cqe(ctx, user_data, res, cflags);
 	io_cq_unlock_post(ctx);
 	return filled;
 }
 
+/*
+ * Must be called from inline task_work so we now a flush will happen later,
+ * and obviously with ctx->uring_lock held (tw always has that).
+ */
+void io_add_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
+{
+	__io_post_aux_cqe(ctx, user_data, res, cflags);
+	ctx->submit_state.cq_flush = true;
+}
+
 /*
  * A helper for multishot requests posting additional CQEs.
  * Should only be used from a task_work including IO_URING_F_MULTISHOT.

io_uring/io_uring.h

@@ -65,6 +65,7 @@ bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow);
 int io_run_task_work_sig(struct io_ring_ctx *ctx);
 void io_req_defer_failed(struct io_kiocb *req, s32 res);
 bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
+void io_add_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
 bool io_req_post_cqe(struct io_kiocb *req, s32 res, u32 cflags);
 void __io_commit_cqring_flush(struct io_ring_ctx *ctx);