netdev - Re: [PATCH net-next] net: add net device refcount tracker to struct packet

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Message-ID: <72c76cf5-b6c2-44a6-865c-deaf7cebf956@redhat.com>
Date:   Thu, 16 Dec 2021 21:33:02 -0500
From:   Jon Maloy <jmaloy@...hat.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Ying Xue <ying.xue@...driver.com>
Subject: Re: [PATCH net-next] net: add net device refcount tracker to struct
 packet_type



On 12/14/21 10:09, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> Most notable changes are in af_packet, tipc ones are trivial.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Jon Maloy <jmaloy@...hat.com>
> Cc: Ying Xue <ying.xue@...driver.com>
> ---
>   include/linux/netdevice.h |  1 +
>   net/packet/af_packet.c    | 14 +++++++++++---
>   net/tipc/bearer.c         |  4 ++--
>   3 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 235d5d082f1a446c8d898ffcc5b1983df7c04f35..0ed0a6f0d69d3565c1db9203040838801cd71e99 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -2533,6 +2533,7 @@ struct packet_type {
>   	__be16			type;	/* This is really htons(ether_type). */
>   	bool			ignore_outgoing;
>   	struct net_device	*dev;	/* NULL is wildcarded here	     */
> +	netdevice_tracker	dev_tracker;
>   	int			(*func) (struct sk_buff *,
>   					 struct net_device *,
>   					 struct packet_type *,
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index a1ffdb48cc474dcf91bddfd1ab96386a89c20375..71854a16afbbc1c06005e48a65cdb7007d61b019 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -3109,7 +3109,7 @@ static int packet_release(struct socket *sock)
>   	packet_cached_dev_reset(po);
>   
>   	if (po->prot_hook.dev) {
> -		dev_put(po->prot_hook.dev);
> +		dev_put_track(po->prot_hook.dev, &po->prot_hook.dev_tracker);
>   		po->prot_hook.dev = NULL;
>   	}
>   	spin_unlock(&po->bind_lock);
> @@ -3217,18 +3217,25 @@ static int packet_do_bind(struct sock *sk, const char *name, int ifindex,
>   		WRITE_ONCE(po->num, proto);
>   		po->prot_hook.type = proto;
>   
> +		dev_put_track(dev_curr, &po->prot_hook.dev_tracker);
> +		dev_curr = NULL;
> +
>   		if (unlikely(unlisted)) {
>   			dev_put(dev);
>   			po->prot_hook.dev = NULL;
>   			WRITE_ONCE(po->ifindex, -1);
>   			packet_cached_dev_reset(po);
>   		} else {
> +			if (dev)
> +				netdev_tracker_alloc(dev,
> +						     &po->prot_hook.dev_tracker,
> +						     GFP_ATOMIC);
>   			po->prot_hook.dev = dev;
>   			WRITE_ONCE(po->ifindex, dev ? dev->ifindex : 0);
>   			packet_cached_dev_assign(po, dev);
>   		}
>   	}
> -	dev_put(dev_curr);
> +	dev_put_track(dev_curr, &po->prot_hook.dev_tracker);
>   
>   	if (proto == 0 || !need_rehook)
>   		goto out_unlock;
> @@ -4138,7 +4145,8 @@ static int packet_notifier(struct notifier_block *this,
>   				if (msg == NETDEV_UNREGISTER) {
>   					packet_cached_dev_reset(po);
>   					WRITE_ONCE(po->ifindex, -1);
> -					dev_put(po->prot_hook.dev);
> +					dev_put_track(po->prot_hook.dev,
> +						      &po->prot_hook.dev_tracker);
>   					po->prot_hook.dev = NULL;
>   				}
>   				spin_unlock(&po->bind_lock);
> diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
> index 60bc74b76adc5909fdb5294f205229682a09d031..473a790f58943537896c16c72b60061b5ffe6840 100644
> --- a/net/tipc/bearer.c
> +++ b/net/tipc/bearer.c
> @@ -787,7 +787,7 @@ int tipc_attach_loopback(struct net *net)
>   	if (!dev)
>   		return -ENODEV;
>   
> -	dev_hold(dev);
> +	dev_hold_track(dev, &tn->loopback_pt.dev_tracker, GFP_KERNEL);
>   	tn->loopback_pt.dev = dev;
>   	tn->loopback_pt.type = htons(ETH_P_TIPC);
>   	tn->loopback_pt.func = tipc_loopback_rcv_pkt;
> @@ -800,7 +800,7 @@ void tipc_detach_loopback(struct net *net)
>   	struct tipc_net *tn = tipc_net(net);
>   
>   	dev_remove_pack(&tn->loopback_pt);
> -	dev_put(net->loopback_dev);
> +	dev_put_track(net->loopback_dev, &tn->loopback_pt.dev_tracker);
>   }
>   
>   /* Caller should hold rtnl_lock to protect the bearer */
Acked-by: Jon Maloy <jmaloy@...hat.com>