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From: Jens Axboe <axboe@kernel.dk>
To: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	io-uring@vger.kernel.org
Subject: [PATCH] io-wq: use proper nesting IRQ disabling spinlocks for cancel
Date: Tue, 5 Nov 2019 13:53:31 -0700
Message-ID: <294dec15-76ac-7475-eba5-0d06c9dc403e@kernel.dk> (raw)

We don't know what context we'll be called in for cancel, it could very
well be with IRQs disabled already. Use the IRQ saving variants of the
locking primitives.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 3bbab2c58695..ba40a7ee31c3 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -642,19 +642,20 @@ static bool io_work_cancel(struct io_worker *worker, void *cancel_data)
 {
 	struct io_cb_cancel_data *data = cancel_data;
 	struct io_wqe *wqe = data->wqe;
+	unsigned long flags;
 	bool ret = false;
 
 	/*
 	 * Hold the lock to avoid ->cur_work going out of scope, caller
 	 * may deference the passed in work.
 	 */
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	if (worker->cur_work &&
 	    data->cancel(worker->cur_work, data->caller_data)) {
 		send_sig(SIGINT, worker->task, 1);
 		ret = true;
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	return ret;
 }
@@ -669,9 +670,10 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
 		.caller_data = cancel_data,
 	};
 	struct io_wq_work *work;
+	unsigned long flags;
 	bool found = false;
 
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	list_for_each_entry(work, &wqe->work_list, list) {
 		if (cancel(work, cancel_data)) {
 			list_del(&work->list);
@@ -679,7 +681,7 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
 			break;
 		}
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	if (found) {
 		work->flags |= IO_WQ_WORK_CANCEL;
@@ -733,6 +735,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 					    struct io_wq_work *cwork)
 {
 	struct io_wq_work *work;
+	unsigned long flags;
 	bool found = false;
 
 	cwork->flags |= IO_WQ_WORK_CANCEL;
@@ -742,7 +745,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	 * from there. CANCEL_OK means that the work is returned as-new,
 	 * no completion will be posted for it.
 	 */
-	spin_lock_irq(&wqe->lock);
+	spin_lock_irqsave(&wqe->lock, flags);
 	list_for_each_entry(work, &wqe->work_list, list) {
 		if (work == cwork) {
 			list_del(&work->list);
@@ -750,7 +753,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 			break;
 		}
 	}
-	spin_unlock_irq(&wqe->lock);
+	spin_unlock_irqrestore(&wqe->lock, flags);
 
 	if (found) {
 		work->flags |= IO_WQ_WORK_CANCEL;

-- 
Jens Axboe


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