linux-kernel - [PATCH 1/1] io-wq: close cancel gap for hashed linked work

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Date:   Sun, 22 Mar 2020 19:14:26 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] io-wq: close cancel gap for hashed linked work

After io_assign_current_work() of a linked work, it can be decided to
offloaded to another thread so doing io_wqe_enqueue(). However, until
next io_assign_current_work() it can be cancelled, that isn't handled.

Don't assign it, if it's not going to be executed.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io-wq.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 9541df2729de..b3fb61ec0870 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -485,7 +485,7 @@ static void io_worker_handle_work(struct io_worker *worker)
 	struct io_wq *wq = wqe->wq;
 
 	do {
-		struct io_wq_work *work;
+		struct io_wq_work *work, *assign_work;
 		unsigned int hash;
 get_next:
 		/*
@@ -522,10 +522,14 @@ static void io_worker_handle_work(struct io_worker *worker)
 			hash = io_get_work_hash(work);
 			work->func(&work);
 			work = (old_work == work) ? NULL : work;
-			io_assign_current_work(worker, work);
+
+			assign_work = work;
+			if (work && io_wq_is_hashed(work))
+				assign_work = NULL;
+			io_assign_current_work(worker, assign_work);
 			wq->free_work(old_work);
 
-			if (work && io_wq_is_hashed(work)) {
+			if (work && !assign_work) {
 				io_wqe_enqueue(wqe, work);
 				work = NULL;
 			}
-- 
2.24.0