virtio_net: Fix missed rtnl_unlock

The rtnl_lock would stay locked if allocating promisc_allmulti failed.
Also changed the allocation to GFP_KERNEL.

Fixes: ff7c7d9f ("virtio_net: Remove command data from control_buf")
Reported-by: Eric Dumazet <edumaset@google.com>
Link: https://lore.kernel.org/netdev/CANn89iLazVaUCvhPm6RPJJ0owra_oFnx7Fhc8d60gV-65ad3WQ@mail.gmail.com/Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20240515163125.569743-1-danielj@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/virtio_net.c

@@ -2902,14 +2902,14 @@ static void virtnet_rx_mode_work(struct work_struct *work)
 	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_RX))
 		return;
 
-	rtnl_lock();
-
-	promisc_allmulti = kzalloc(sizeof(*promisc_allmulti), GFP_ATOMIC);
+	promisc_allmulti = kzalloc(sizeof(*promisc_allmulti), GFP_KERNEL);
 	if (!promisc_allmulti) {
 		dev_warn(&dev->dev, "Failed to set RX mode, no memory.\n");
 		return;
 	}
 
+	rtnl_lock();
+
 	*promisc_allmulti = !!(dev->flags & IFF_PROMISC);
 	sg_init_one(sg, promisc_allmulti, sizeof(*promisc_allmulti));