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

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

[Bart Van Assche]

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.

Tested-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
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 e18fa260a662..1f8ffdf9b24e 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -3443,8 +3443,10 @@ 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;
 		}
 	}
@@ -3693,8 +3695,10 @@ 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;
 	}

Re: [PATCH] drbd: Balance RCU calls in drbd_adm_dump_devices()

[Bart Van Assche]

On 3/26/26 2:40 PM, Bart Van Assche wrote:
> 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.

(replying to my own email)

Since it is the third time this patch is posted, the changelog is as
follows:

Changes compared to v2:
  - Added Christoph Hellwig's Reviewed-by tag.
  - Extracted this patch from a larger series.

Changes compared to v1:
  - Added Christoph Böhmwalder's Tested-by tag.

Bart.

Re: [PATCH] drbd: Balance RCU calls in drbd_adm_dump_devices()

[Jens Axboe]

On Thu, 26 Mar 2026 14:40:54 -0700, Bart Van Assche wrote:
> 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.

Applied, thanks!

[1/1] drbd: Balance RCU calls in drbd_adm_dump_devices()
      commit: 2b31e86387e60b3689339f0f0fbb4d3623d9d494

Best regards,
-- 
Jens Axboe