Re: [PATCH] Hyperv: Trigger DHCP renew after host hibernation

Richard Weinberger
2014-07-18T13:40:59Z

On Fri, Jul 18, 2014 at 12:55 PM, Yue Zhang <yuezha@microsoft.com> wrote:
> From: Yue Zhang <yuezha@microsoft.com>
>
> This patch addresses the comment from Olaf Hering and Greg KH
> for a previous commit 3a494e710367 ("hyperv: Add handler for
> RNDIS_STATUS_NETWORK_CHANGE event")
>
> In previous solution, the driver calls "network restart" to
> force a DHCP renew when the host is back from hibernation.
>
> In this fix, the driver will keep network carrier offline for
> 10 seconds and then bring it back. So that ifplugd daemon will
> notice this change and refresh DHCP lease.
>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: K. Y. Srinivasan <kys@microsoft.com>
>
> Signed-off-by: Yue Zhang <yuezha@microsoft.com>
> ---
> drivers/net/hyperv/netvsc_drv.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index a9c5eaa..559c97d 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -33,6 +33,7 @@
> #include <linux/if_vlan.h>
> #include <linux/in.h>
> #include <linux/slab.h>
> +#include <linux/delay.h>
> #include <net/arp.h>
> #include <net/route.h>
> #include <net/sock.h>
> @@ -792,8 +793,7 @@ static void netvsc_link_change(struct work_struct *w)
> struct netvsc_device *net_device;
> struct rndis_device *rdev;
> bool notify, refresh = false;
> - char *argv[] = { "/etc/init.d/network", "restart", NULL };
> - char *envp[] = { "HOME=/", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
> + int delay;
>
> rtnl_lock();
>
> @@ -816,8 +816,21 @@ static void netvsc_link_change(struct work_struct *w)
>
> rtnl_unlock();
>
> - if (refresh)
> - call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
> + if (refresh) {
> + /*
> + * Keep the carrier offline for 10 seconds
> + * to notify ifplugd daemon network change
> + */

Why 10? Is this a random number which works by accident for ifplugd?
What about other networking implementations, is 10 also ok for them?

> + for (delay = 0; delay < 10; delay++) {
> + rtnl_lock();
> + netif_carrier_off(net);
> + rtnl_unlock();
> + ssleep(1);
> + }
> + rtnl_lock();
> + netif_carrier_on(net);
> + rtnl_unlock();
> + }
>
> if (notify)
> netdev_notify_peers(net);
> --
> 1.9.1
>
> --
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--
Thanks,
//richard