[PATCH net-next 7/8] netvsc: save pointer to parent netvsc_device in channel table

[Stephen Hemminger]

Keep back pointer in the per-channel data structure to
avoid any possible RCU related issues when napi poll is
called but netvsc_device is in RCU limbo.

Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h | 1 +
 drivers/net/hyperv/netvsc.c     | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 0054b6929f6e..d13572879e7e 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -727,6 +727,7 @@ struct net_device_context {
 /* Per channel data */
 struct netvsc_channel {
        struct vmbus_channel *channel;
+       struct netvsc_device *net_device;
        const struct vmpacket_descriptor *desc;
        struct napi_struct napi;
        struct multi_send_data msd;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 3c6f3ae520d9..c15640c6fd83 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1224,11 +1224,11 @@ int netvsc_poll(struct napi_struct *napi, int budget)
 {
        struct netvsc_channel *nvchan
                = container_of(napi, struct netvsc_channel, napi);
+       struct netvsc_device *net_device = nvchan->net_device;
        struct vmbus_channel *channel = nvchan->channel;
        struct hv_device *device = netvsc_channel_to_device(channel);
        u16 q_idx = channel->offermsg.offer.sub_channel_index;
        struct net_device *ndev = hv_get_drvdata(device);
-       struct netvsc_device *net_device = net_device_to_netvsc_device(ndev);
        int work_done = 0;
 
        /* If starting a new interval */
@@ -1307,6 +1307,7 @@ struct netvsc_device *netvsc_device_add(struct hv_device 
*device,
                struct netvsc_channel *nvchan = &net_device->chan_table[i];
 
                nvchan->channel = device->channel;
+               nvchan->net_device = net_device;
        }
 
        /* Enable NAPI handler before init callbacks */
-- 
2.11.0