[PATCH AUTOSEL 5.8 06/64] loop: be paranoid on exit and prevent new additions / removals

From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>,
	Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>,
	linux-block@vger.kernel.org
Subject: [PATCH AUTOSEL 5.8 06/64] loop: be paranoid on exit and prevent new additions / removals
Date: Mon, 10 Aug 2020 15:08:01 -0400	[thread overview]
Message-ID: <20200810190859.3793319-6-sashal@kernel.org> (raw)
In-Reply-To: <20200810190859.3793319-1-sashal@kernel.org>

From: Luis Chamberlain <mcgrof@kernel.org>

[ Upstream commit 200f93377220504c5e56754823e7adfea6037f1a ]

Be pedantic on removal as well and hold the mutex.
This should prevent uses of addition while we exit.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/loop.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 475e1a738560d..776083963ee6c 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2402,6 +2402,8 @@ static void __exit loop_exit(void)
 
 	range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
 
+	mutex_lock(&loop_ctl_mutex);
+
 	idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
 	idr_destroy(&loop_index_idr);
 
@@ -2409,6 +2411,8 @@ static void __exit loop_exit(void)
 	unregister_blkdev(LOOP_MAJOR, "loop");
 
 	misc_deregister(&loop_misc);
+
+	mutex_unlock(&loop_ctl_mutex);
 }
 
 module_init(loop_init);
-- 
2.25.1

