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[RFC,net-next,0/3] lockless version of

Message ID 20201206052127.21450-1-ljp@linux.ibm.com
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Series lockless version of | expand

Message

Lijun Pan Dec. 6, 2020, 5:21 a.m. UTC 
This series introduce the lockless version of netdev_notify_peers
and then apply it to the relevant drivers.

Lijun Pan (3):
  net: core: introduce netdev_notify_peers_locked
  use netdev_notify_peers_locked in ibmvnic
  use netdev_notify_peers_locked in hyperv

 drivers/net/ethernet/ibm/ibmvnic.c |  9 +++------
 drivers/net/hyperv/netvsc_drv.c    |  6 +++---
 include/linux/netdevice.h          |  1 +
 net/core/dev.c                     | 19 +++++++++++++++++++
 4 files changed, 26 insertions(+), 9 deletions(-)

Comments

Jakub Kicinski Dec. 8, 2020, 11:49 p.m. UTC | #1 
On Sat,  5 Dec 2020 23:21:25 -0600 Lijun Pan wrote:
> There are some use cases for netdev_notify_peers in the context

> when rtnl lock is already held. Introduce lockless version

> of netdev_notify_peers call to save the extra code to call

> 	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);

> 	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);

> 

> Suggested-by: Nathan Lynch <nathanl@linux.ibm.com>

> Signed-off-by: Lijun Pan <ljp@linux.ibm.com>


> --- a/net/core/dev.c

> +++ b/net/core/dev.c

> @@ -1488,6 +1488,25 @@ void netdev_notify_peers(struct net_device *dev)

>  }

>  EXPORT_SYMBOL(netdev_notify_peers);


Why not convert netdev_notify_peers to call the new helper?
That way the chance they will get out of sync is way smaller.

> +/**

> + * netdev_notify_peers_locked - notify network peers about existence of @dev,

> + * to be called in the context when rtnl lock is already held.

> + * @dev: network device

> + *

> + * Generate traffic such that interested network peers are aware of

> + * @dev, such as by generating a gratuitous ARP. This may be used when

> + * a device wants to inform the rest of the network about some sort of

> + * reconfiguration such as a failover event or virtual machine

> + * migration.

> + */

> +void netdev_notify_peers_locked(struct net_device *dev)


I think __netdev_notify_peers() would be a more typical name for
a core kernel function like this.

> +{

> +	ASSERT_RTNL();

> +	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);

> +	call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);

> +}

> +EXPORT_SYMBOL(netdev_notify_peers_locked);


Otherwise LGTM, seems like a good cleanup.