[PATCH net-next v2 01/11] net: bubble up taking netdev instance lock to callers of net_devmem_unbind_dmabuf()

[Jakub Kicinski <kuba@kernel.org>]

A recent commit added taking the netdev instance lock
in netdev_nl_bind_rx_doit(), but didn't remove it in
net_devmem_unbind_dmabuf() which it calls from an error path.
Always expect the callers of net_devmem_unbind_dmabuf() to
hold the lock. This is consistent with net_devmem_bind_dmabuf().

(Not so) coincidentally this also protects mp_param with the instance
lock, which the rest of this series needs.

Fixes: 1d22d3060b9b ("net: drop rtnl_lock for queue_mgmt operations")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - rebase on a70f891e0fa0 ("net: devmem: do not WARN conditionally after netdev_rx_queue_restart()")
v1: https://lore.kernel.org/20250312223507.805719-2-kuba@kernel.org
---
 net/core/devmem.c      | 2 --
 net/core/netdev-genl.c | 2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/devmem.c b/net/core/devmem.c
index 6802e82a4d03..ee145a2aa41c 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -128,12 +128,10 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 		rxq->mp_params.mp_priv = NULL;
 		rxq->mp_params.mp_ops = NULL;
 
-		netdev_lock(binding->dev);
 		rxq_idx = get_netdev_rx_queue_index(rxq);
 
 		err = netdev_rx_queue_restart(binding->dev, rxq_idx);
 		WARN_ON(err && err != -ENETDOWN);
-		netdev_unlock(binding->dev);
 	}
 
 	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index a186fea63c09..9e4882a22407 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -947,7 +947,9 @@ void netdev_nl_sock_priv_destroy(struct netdev_nl_sock *priv)
 
 	mutex_lock(&priv->lock);
 	list_for_each_entry_safe(binding, temp, &priv->bindings, list) {
+		netdev_lock(binding->dev);
 		net_devmem_unbind_dmabuf(binding);
+		netdev_unlock(binding->dev);
 	}
 	mutex_unlock(&priv->lock);
 }
-- 
2.49.0