io_uring: encapsulate task_work state

For task works we're passing around a bool pointer for whether the
current ring is locked or not, let's wrap it in a structure, that
will make it more opaque preventing abuse and will also help us
to pass more info in the future if needed.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1ecec9483d58696e248d1bfd52cf62b04442df1d.1679931367.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 36 insertions, 35 deletions

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 2669aca0ba39..536940675c67 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -247,12 +247,12 @@ static __cold void io_fallback_req_func(struct work_struct *work)
 						fallback_work.work);
 	struct llist_node *node = llist_del_all(&ctx->fallback_llist);
 	struct io_kiocb *req, *tmp;
-	bool locked = true;
+	struct io_tw_state ts = { .locked = true, };
 
 	mutex_lock(&ctx->uring_lock);
 	llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
-		req->io_task_work.func(req, &locked);
-	if (WARN_ON_ONCE(!locked))
+		req->io_task_work.func(req, &ts);
+	if (WARN_ON_ONCE(!ts.locked))
 		return;
 	io_submit_flush_completions(ctx);
 	mutex_unlock(&ctx->uring_lock);
@@ -457,7 +457,7 @@ static void io_prep_async_link(struct io_kiocb *req)
 	}
 }
 
-void io_queue_iowq(struct io_kiocb *req, bool *dont_use)
+void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use)
 {
 	struct io_kiocb *link = io_prep_linked_timeout(req);
 	struct io_uring_task *tctx = req->task->io_uring;
@@ -1153,22 +1153,23 @@ static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 	return nxt;
 }
 
-static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
+static void ctx_flush_and_put(struct io_ring_ctx *ctx, struct io_tw_state *ts)
 {
 	if (!ctx)
 		return;
 	if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
 		atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
-	if (*locked) {
+	if (ts->locked) {
 		io_submit_flush_completions(ctx);
 		mutex_unlock(&ctx->uring_lock);
-		*locked = false;
+		ts->locked = false;
 	}
 	percpu_ref_put(&ctx->refs);
 }
 
 static unsigned int handle_tw_list(struct llist_node *node,
-				   struct io_ring_ctx **ctx, bool *locked,
+				   struct io_ring_ctx **ctx,
+				   struct io_tw_state *ts,
 				   struct llist_node *last)
 {
 	unsigned int count = 0;
@@ -1181,17 +1182,17 @@ static unsigned int handle_tw_list(struct llist_node *node,
 		prefetch(container_of(next, struct io_kiocb, io_task_work.node));
 
 		if (req->ctx != *ctx) {
-			ctx_flush_and_put(*ctx, locked);
+			ctx_flush_and_put(*ctx, ts);
 			*ctx = req->ctx;
 			/* if not contended, grab and improve batching */
-			*locked = mutex_trylock(&(*ctx)->uring_lock);
+			ts->locked = mutex_trylock(&(*ctx)->uring_lock);
 			percpu_ref_get(&(*ctx)->refs);
 		}
-		req->io_task_work.func(req, locked);
+		req->io_task_work.func(req, ts);
 		node = next;
 		count++;
 		if (unlikely(need_resched())) {
-			ctx_flush_and_put(*ctx, locked);
+			ctx_flush_and_put(*ctx, ts);
 			*ctx = NULL;
 			cond_resched();
 		}
@@ -1232,7 +1233,7 @@ static inline struct llist_node *io_llist_cmpxchg(struct llist_head *head,
 
 void tctx_task_work(struct callback_head *cb)
 {
-	bool uring_locked = false;
+	struct io_tw_state ts = {};
 	struct io_ring_ctx *ctx = NULL;
 	struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
 						  task_work);
@@ -1249,12 +1250,12 @@ void tctx_task_work(struct callback_head *cb)
 	do {
 		loops++;
 		node = io_llist_xchg(&tctx->task_list, &fake);
-		count += handle_tw_list(node, &ctx, &uring_locked, &fake);
+		count += handle_tw_list(node, &ctx, &ts, &fake);
 
 		/* skip expensive cmpxchg if there are items in the list */
 		if (READ_ONCE(tctx->task_list.first) != &fake)
 			continue;
-		if (uring_locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) {
+		if (ts.locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) {
 			io_submit_flush_completions(ctx);
 			if (READ_ONCE(tctx->task_list.first) != &fake)
 				continue;
@@ -1262,7 +1263,7 @@ void tctx_task_work(struct callback_head *cb)
 		node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);
 	} while (node != &fake);
 
-	ctx_flush_and_put(ctx, &uring_locked);
+	ctx_flush_and_put(ctx, &ts);
 
 	/* relaxed read is enough as only the task itself sets ->in_cancel */
 	if (unlikely(atomic_read(&tctx->in_cancel)))
@@ -1351,7 +1352,7 @@ static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
 	}
 }
 
-static int __io_run_local_work(struct io_ring_ctx *ctx, bool *locked)
+static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts)
 {
 	struct llist_node *node;
 	unsigned int loops = 0;
@@ -1368,7 +1369,7 @@ again:
 		struct io_kiocb *req = container_of(node, struct io_kiocb,
 						    io_task_work.node);
 		prefetch(container_of(next, struct io_kiocb, io_task_work.node));
-		req->io_task_work.func(req, locked);
+		req->io_task_work.func(req, ts);
 		ret++;
 		node = next;
 	}
@@ -1376,7 +1377,7 @@ again:
 
 	if (!llist_empty(&ctx->work_llist))
 		goto again;
-	if (*locked) {
+	if (ts->locked) {
 		io_submit_flush_completions(ctx);
 		if (!llist_empty(&ctx->work_llist))
 			goto again;
@@ -1387,46 +1388,46 @@ again:
 
 static inline int io_run_local_work_locked(struct io_ring_ctx *ctx)
 {
-	bool locked;
+	struct io_tw_state ts = { .locked = true, };
 	int ret;
 
 	if (llist_empty(&ctx->work_llist))
 		return 0;
 
-	locked = true;
-	ret = __io_run_local_work(ctx, &locked);
+	ret = __io_run_local_work(ctx, &ts);
 	/* shouldn't happen! */
-	if (WARN_ON_ONCE(!locked))
+	if (WARN_ON_ONCE(!ts.locked))
 		mutex_lock(&ctx->uring_lock);
 	return ret;
 }
 
 static int io_run_local_work(struct io_ring_ctx *ctx)
 {
-	bool locked = mutex_trylock(&ctx->uring_lock);
+	struct io_tw_state ts = {};
 	int ret;
 
-	ret = __io_run_local_work(ctx, &locked);
-	if (locked)
+	ts.locked = mutex_trylock(&ctx->uring_lock);
+	ret = __io_run_local_work(ctx, &ts);
+	if (ts.locked)
 		mutex_unlock(&ctx->uring_lock);
 
 	return ret;
 }
 
-static void io_req_task_cancel(struct io_kiocb *req, bool *locked)
+static void io_req_task_cancel(struct io_kiocb *req, struct io_tw_state *ts)
 {
-	io_tw_lock(req->ctx, locked);
+	io_tw_lock(req->ctx, ts);
 	io_req_defer_failed(req, req->cqe.res);
 }
 
-void io_req_task_submit(struct io_kiocb *req, bool *locked)
+void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts)
 {
-	io_tw_lock(req->ctx, locked);
+	io_tw_lock(req->ctx, ts);
 	/* req->task == current here, checking PF_EXITING is safe */
 	if (unlikely(req->task->flags & PF_EXITING))
 		io_req_defer_failed(req, -EFAULT);
 	else if (req->flags & REQ_F_FORCE_ASYNC)
-		io_queue_iowq(req, locked);
+		io_queue_iowq(req, ts);
 	else
 		io_queue_sqe(req);
 }
@@ -1652,9 +1653,9 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 	return ret;
 }
 
-void io_req_task_complete(struct io_kiocb *req, bool *locked)
+void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts)
 {
-	if (*locked)
+	if (ts->locked)
 		io_req_complete_defer(req);
 	else
 		io_req_complete_post(req, IO_URING_F_UNLOCKED);
@@ -1933,9 +1934,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
-int io_poll_issue(struct io_kiocb *req, bool *locked)
+int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts)
 {
-	io_tw_lock(req->ctx, locked);
+	io_tw_lock(req->ctx, ts);
 	return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_MULTISHOT|
 				 IO_URING_F_COMPLETE_DEFER);
 }