linux-kernel - [PATCH AUTOSEL 5.11 58/61] io_uring: cancel deferred requests in try

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Date:   Tue, 16 Mar 2021 20:55:32 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        io-uring@...r.kernel.org
Subject: [PATCH AUTOSEL 5.11 58/61] io_uring: cancel deferred requests in try_cancel

From: Pavel Begunkov <asml.silence@...il.com>

[ Upstream commit e1915f76a8981f0a750cf56515df42582a37c4b0 ]

As io_uring_cancel_files() and others let SQO to run between
io_uring_try_cancel_requests(), SQO may generate new deferred requests,
so it's safer to try to cancel them in it.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io_uring.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 241313278e5a..89708ffc1c2b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8848,11 +8848,11 @@ static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
 	return ret;
 }
 
-static void io_cancel_defer_files(struct io_ring_ctx *ctx,
+static bool io_cancel_defer_files(struct io_ring_ctx *ctx,
 				  struct task_struct *task,
 				  struct files_struct *files)
 {
-	struct io_defer_entry *de = NULL;
+	struct io_defer_entry *de;
 	LIST_HEAD(list);
 
 	spin_lock_irq(&ctx->completion_lock);
@@ -8863,6 +8863,8 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx,
 		}
 	}
 	spin_unlock_irq(&ctx->completion_lock);
+	if (list_empty(&list))
+		return false;
 
 	while (!list_empty(&list)) {
 		de = list_first_entry(&list, struct io_defer_entry, list);
@@ -8872,6 +8874,7 @@ static void io_cancel_defer_files(struct io_ring_ctx *ctx,
 		io_req_complete(de->req, -ECANCELED);
 		kfree(de);
 	}
+	return true;
 }
 
 static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
@@ -8898,6 +8901,7 @@ static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
 			}
 		}
 
+		ret |= io_cancel_defer_files(ctx, task, files);
 		ret |= io_poll_remove_all(ctx, task, files);
 		ret |= io_kill_timeouts(ctx, task, files);
 		ret |= io_run_task_work();
@@ -8976,8 +8980,6 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 		io_sq_thread_park(ctx->sq_data);
 	}
 
-	io_cancel_defer_files(ctx, task, files);
-
 	io_uring_cancel_files(ctx, task, files);
 	if (!files)
 		io_uring_try_cancel_requests(ctx, task, NULL);
-- 
2.30.1