linux-kernel - [PATCH 1/1] block/drbd/drbd_debugfs.c: Protect &connection->kref with resource->req

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Message-Id: <1574742858-23131-1-git-send-email-KC17041980@gmail.com>
Date:   Tue, 26 Nov 2019 10:04:18 +0530
From:   kc27041980@...il.com
To:     Philipp Reisner <philipp.reisner@...bit.com>,
        Lars Ellenberg <lars.ellenberg@...bit.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, KC27041980 <kc27041980@...il.com>
Subject: [PATCH 1/1] block/drbd/drbd_debugfs.c: Protect &connection->kref with resource->req_lock

From: KC27041980 <kc27041980@...il.com>

Protect &connection->kref by moving it under resource->req_lock.

Signed-off-by: KC27041980 <kc27041980@...il.com>
---
 drivers/block/drbd/drbd_debugfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/block/drbd/drbd_debugfs.c b/drivers/block/drbd/drbd_debugfs.c
index b3b9cd5..f6d75fa 100644
--- a/drivers/block/drbd/drbd_debugfs.c
+++ b/drivers/block/drbd/drbd_debugfs.c
@@ -363,11 +363,15 @@ static int in_flight_summary_show(struct seq_file *m, void *pos)
 	struct drbd_connection *connection;
 	unsigned long jif = jiffies;
 
+	spin_lock_irq(&resource->req_lock);
 	connection = first_connection(resource);
 	/* This does not happen, actually.
 	 * But be robust and prepare for future code changes. */
-	if (!connection || !kref_get_unless_zero(&connection->kref))
+	if (!connection || !kref_get_unless_zero(&connection->kref)) {
+		spin_unlock_irq(&resource->req_lock);
 		return -ESTALE;
+	}
+	spin_unlock_irq(&resource->req_lock);
 
 	/* BUMP me if you change the file format/content/presentation */
 	seq_printf(m, "v: %u\n\n", 0);
-- 
2.7.4