[PATCH 03/62] drbd: Balance RCU calls in drbd_adm_dump_devices()

[Bart Van Assche <bart.vanassche@linux.dev>]

From: Bart Van Assche <bvanassche@acm.org>

Make drbd_adm_dump_devices() call rcu_read_lock() before
rcu_read_unlock() is called. This has been detected by the Clang
thread-safety analyzer. Compile-tested only.

Cc: Andreas Gruenbacher <agruen@linbit.com>
Cc: linux-block@vger.kernel.org
Fixes: a55bbd375d18 ("drbd: Backport the "status" command")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/block/drbd/drbd_nl.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index e201f0087a0f..728ecc431b38 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -3378,8 +3378,10 @@ int drbd_adm_dump_devices(struct sk_buff *skb, struct netlink_callback *cb)
 		if (resource_filter) {
 			retcode = ERR_RES_NOT_KNOWN;
 			resource = drbd_find_resource(nla_data(resource_filter));
-			if (!resource)
+			if (!resource) {
+				rcu_read_lock();
 				goto put_result;
+			}
 			cb->args[0] = (long)resource;
 		}
 	}
@@ -3628,8 +3630,10 @@ int drbd_adm_dump_peer_devices(struct sk_buff *skb, struct netlink_callback *cb)
 		if (resource_filter) {
 			retcode = ERR_RES_NOT_KNOWN;
 			resource = drbd_find_resource(nla_data(resource_filter));
-			if (!resource)
+			if (!resource) {
+				rcu_read_lock();
 				goto put_result;
+			}
 		}
 		cb->args[0] = (long)resource;
 	}