From: Marcin Dziegielewski <marcin.dziegielewski@intel.com>
Date: Sat, 4 May 2019 18:37:58 +0000 (+0200)
Subject: lightnvm: prevent race condition on pblk remove
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=f41d427cdd9ec379e35777d13622c3cd382bf0a2;p=openwrt%2Fstaging%2Fblogic.git

lightnvm: prevent race condition on pblk remove

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

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;
 }