[PATCH net-next v2 5/6] hv_netvsc: synchronize netvsc_change_mtu()/netvsc_set_channels() with netvsc_remove()

From: Vitaly Kuznetsov
Date: Fri May 13 2016 - 07:56:51 EST


When netvsc device is removed during mtu change or channels setup we get
into troubles as both paths are trying to remove the device. Synchronize
them with start_remove flag and rtnl lock.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/net/hyperv/netvsc_drv.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 7325d69..6a69b5c 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -759,7 +759,7 @@ static int netvsc_set_channels(struct net_device *net,
int ret = 0;
bool recovering = false;

- if (!nvdev || nvdev->destroy)
+ if (net_device_ctx->start_remove || !nvdev || nvdev->destroy)
return -ENODEV;

num_chn = nvdev->num_chn;
@@ -907,7 +907,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
u32 num_chn;
int ret = 0;

- if (nvdev == NULL || nvdev->destroy)
+ if (ndevctx->start_remove || !nvdev || nvdev->destroy)
return -ENODEV;

if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
@@ -1445,7 +1445,12 @@ static int netvsc_remove(struct hv_device *dev)
ndev_ctx = netdev_priv(net);
net_device = ndev_ctx->nvdev;

+ /* Avoid racing with netvsc_change_mtu()/netvsc_set_channels()
+ * removing the device.
+ */
+ rtnl_lock();
ndev_ctx->start_remove = true;
+ rtnl_unlock();

cancel_delayed_work_sync(&ndev_ctx->dwork);
cancel_work_sync(&ndev_ctx->work);
--
2.5.5