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From:   =?UTF-8?q?Matias=20Bj=C3=B8rling?= <mb@lightnvm.io>
To:     axboe@fb.com
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        Marcin Dziegielewski <marcin.dziegielewski@intel.com>,
        =?UTF-8?q?Matias=20Bj=C3=B8rling?= <mb@lightnvm.io>
Subject: [GIT PULL 13/26] lightnvm: prevent race condition on pblk remove
Date:   Sat,  4 May 2019 20:37:58 +0200
Message-Id: <20190504183811.18725-14-mb@lightnvm.io>
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From: Marcin Dziegielewski <marcin.dziegielewski@intel.com>

When we trigger nvm target remove during device hot unplug, there is
a probability to hit a general protection fault. This is caused by use
of nvm_dev thay may be freed from another (hot unplug) thread
(in the nvm_unregister function).

Introduce lock in nvme_ioctl_dev_remove function to prevent this
situation.

Signed-off-by: Marcin Dziegielewski <marcin.dziegielewski@intel.com>
Reviewed-by: Javier González <javier@javigon.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
---
 drivers/lightnvm/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index c01f83b8fbaf..e2abe88a139c 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -1340,11 +1340,13 @@ static long nvm_ioctl_dev_remove(struct file *file, void __user *arg)
 		return -EINVAL;
 	}
 
+	down_read(&nvm_lock);
 	list_for_each_entry(dev, &nvm_devices, devices) {
 		ret = nvm_remove_tgt(dev, &remove);
 		if (!ret)
 			break;
 	}
+	up_read(&nvm_lock);
 
 	return ret;
 }
-- 
2.19.1