io_uring: name sq thread and ref completions

We used to have three completions, now we just have two. With the two,
let's not allocate them dynamically, just embed then in the ctx and
name them appropriately.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -279,8 +279,8 @@ struct io_ring_ctx {
 
 	const struct cred	*creds;
 
-	/* 0 is for ctx quiesce/reinit/free, 1 is for sqo_thread started */
-	struct completion	*completions;
+	struct completion	ref_comp;
+	struct completion	sq_thread_comp;
 
 	/* if all else fails... */
 	struct io_kiocb		*fallback_req;
@@ -883,7 +883,7 @@ static void io_ring_ctx_ref_free(struct percpu_ref *ref)
 {
 	struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
 
-	complete(&ctx->completions[0]);
+	complete(&ctx->ref_comp);
 }
 
 static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
@@ -899,10 +899,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	if (!ctx->fallback_req)
 		goto err;
 
-	ctx->completions = kmalloc(2 * sizeof(struct completion), GFP_KERNEL);
-	if (!ctx->completions)
-		goto err;
-
 	/*
 	 * Use 5 bits less than the max cq entries, that should give us around
 	 * 32 entries per hash list if totally full and uniformly spread.
@@ -925,8 +921,8 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	ctx->flags = p->flags;
 	init_waitqueue_head(&ctx->cq_wait);
 	INIT_LIST_HEAD(&ctx->cq_overflow_list);
-	init_completion(&ctx->completions[0]);
-	init_completion(&ctx->completions[1]);
+	init_completion(&ctx->ref_comp);
+	init_completion(&ctx->sq_thread_comp);
 	idr_init(&ctx->io_buffer_idr);
 	idr_init(&ctx->personality_idr);
 	mutex_init(&ctx->uring_lock);
@@ -942,7 +938,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 err:
 	if (ctx->fallback_req)
 		kmem_cache_free(req_cachep, ctx->fallback_req);
-	kfree(ctx->completions);
 	kfree(ctx->cancel_hash);
 	kfree(ctx);
 	return NULL;
@@ -5933,7 +5928,7 @@ static int io_sq_thread(void *data)
 	unsigned long timeout;
 	int ret = 0;
 
-	complete(&ctx->completions[1]);
+	complete(&ctx->sq_thread_comp);
 
 	old_fs = get_fs();
 	set_fs(USER_DS);
@@ -6212,7 +6207,7 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 static void io_sq_thread_stop(struct io_ring_ctx *ctx)
 {
 	if (ctx->sqo_thread) {
-		wait_for_completion(&ctx->completions[1]);
+		wait_for_completion(&ctx->sq_thread_comp);
 		/*
 		 * The park is a bit of a work-around, without it we get
 		 * warning spews on shutdown with SQPOLL set and affinity
@@ -7241,7 +7236,6 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 				ring_pages(ctx->sq_entries, ctx->cq_entries));
 	free_uid(ctx->user);
 	put_cred(ctx->creds);
-	kfree(ctx->completions);
 	kfree(ctx->cancel_hash);
 	kmem_cache_free(req_cachep, ctx->fallback_req);
 	kfree(ctx);
@@ -7293,7 +7287,7 @@ static void io_ring_exit_work(struct work_struct *work)
 	if (ctx->rings)
 		io_cqring_overflow_flush(ctx, true);
 
-	wait_for_completion(&ctx->completions[0]);
+	wait_for_completion(&ctx->ref_comp);
 	io_ring_ctx_free(ctx);
 }
 
@@ -7992,7 +7986,7 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 		 * after we've killed the percpu ref.
 		 */
 		mutex_unlock(&ctx->uring_lock);
-		ret = wait_for_completion_interruptible(&ctx->completions[0]);
+		ret = wait_for_completion_interruptible(&ctx->ref_comp);
 		mutex_lock(&ctx->uring_lock);
 		if (ret) {
 			percpu_ref_resurrect(&ctx->refs);
@@ -8069,7 +8063,7 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 		/* bring the ctx back to life */
 		percpu_ref_reinit(&ctx->refs);
 out:
-		reinit_completion(&ctx->completions[0]);
+		reinit_completion(&ctx->ref_comp);
 	}
 	return ret;
 }