4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 963abe5c8a0273a1cf5913556da1b1189de0e57a ]
It seems many drivers do not respect napi_hash_del() contract.
When napi_hash_del() is used before netif_napi_del(), an RCU grace
period is needed before freeing NAPI object.
Fixes: 91815639d880 ("virtio-net: rx busy polling support")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1465,6 +1465,11 @@ static void virtnet_free_queues(struct v
netif_napi_del(&vi->rq[i].napi);
}
+ /* We called napi_hash_del() before netif_napi_del(),
+ * we need to respect an RCU grace period before freeing vi->rq
+ */
+ synchronize_net();
+
kfree(vi->rq);
kfree(vi->sq);
}
--
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