netdev - [net PATCH v2 2/5] net: virtio: wrap rtnl_lock in test for calling with lock already held

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Date:   Thu, 12 Jan 2017 16:35:34 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     jasowang@...hat.com, mst@...hat.com
Cc:     john.r.fastabend@...el.com, netdev@...r.kernel.org,
        john.fastabend@...il.com, alexei.starovoitov@...il.com,
        daniel@...earbox.net
Subject: [net PATCH v2 2/5] net: virtio: wrap rtnl_lock in test for calling
 with lock already held

For XDP use case and to allow ethtool reset tests it is useful to be
able to use reset routines from contexts where rtnl lock is already
held.

Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
---
 drivers/net/virtio_net.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d97bb71..43cb2e0 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1864,12 +1864,13 @@ static void virtnet_free_queues(struct virtnet_info *vi)
 	kfree(vi->sq);
 }
 
-static void free_receive_bufs(struct virtnet_info *vi)
+static void free_receive_bufs(struct virtnet_info *vi, bool need_lock)
 {
 	struct bpf_prog *old_prog;
 	int i;
 
-	rtnl_lock();
+	if (need_lock)
+		rtnl_lock();
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		while (vi->rq[i].pages)
 			__free_pages(get_a_page(&vi->rq[i], GFP_KERNEL), 0);
@@ -1879,7 +1880,8 @@ static void free_receive_bufs(struct virtnet_info *vi)
 		if (old_prog)
 			bpf_prog_put(old_prog);
 	}
-	rtnl_unlock();
+	if (need_lock)
+		rtnl_unlock();
 }
 
 static void free_receive_page_frags(struct virtnet_info *vi)
@@ -2351,14 +2353,14 @@ static int virtnet_probe(struct virtio_device *vdev)
 	return err;
 }
 
-static void remove_vq_common(struct virtnet_info *vi)
+static void remove_vq_common(struct virtnet_info *vi, bool lock)
 {
 	vi->vdev->config->reset(vi->vdev);
 
 	/* Free unused buffers in both send and recv, if any. */
 	free_unused_bufs(vi);
 
-	free_receive_bufs(vi);
+	free_receive_bufs(vi, lock);
 
 	free_receive_page_frags(vi);
 
@@ -2376,7 +2378,7 @@ static void virtnet_remove(struct virtio_device *vdev)
 
 	unregister_netdev(vi->dev);
 
-	remove_vq_common(vi);
+	remove_vq_common(vi, true);
 
 	free_percpu(vi->stats);
 	free_netdev(vi->dev);
@@ -2401,7 +2403,7 @@ static int virtnet_freeze(struct virtio_device *vdev)
 			napi_disable(&vi->rq[i].napi);
 	}
 
-	remove_vq_common(vi);
+	remove_vq_common(vi, true);
 
 	return 0;
 }