netdev - Re: [PATCH v6 2/6] netlink: Add new netlink

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Date: Fri, 30 Jun 2023 20:39:06 +0000
From: Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
To: Liam Howlett <liam.howlett@...cle.com>
CC: "davem@...emloft.net" <davem@...emloft.net>,
        "david@...es.net"
	<david@...es.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "zbr@...emap.net" <zbr@...emap.net>,
        "brauner@...nel.org"
	<brauner@...nel.org>,
        "johannes@...solutions.net"
	<johannes@...solutions.net>,
        "ecree.xilinx@...il.com"
	<ecree.xilinx@...il.com>,
        "leon@...nel.org" <leon@...nel.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "socketcan@...tkopp.net"
	<socketcan@...tkopp.net>,
        "petrm@...dia.com" <petrm@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH v6 2/6] netlink: Add new netlink_release function



> On Jun 30, 2023, at 1:23 PM, Liam Howlett <liam.howlett@...cle.com> wrote:
> 
> * Anjali Kulkarni <anjali.k.kulkarni@...cle.com> [230614 19:41]:
>> A new function netlink_release is added in netlink_sock to store the
>> protocol's release function. This is called when the socket is deleted.
>> This can be supplied by the protocol via the release function in
>> netlink_kernel_cfg. This is being added for the NETLINK_CONNECTOR
>> protocol, so it can free it's data when socket is deleted.
>> 
>> Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
>> ---
>> include/linux/netlink.h | 1 +
>> net/netlink/af_netlink.c | 6 ++++++
>> net/netlink/af_netlink.h | 4 ++++
>> 3 files changed, 11 insertions(+)
>> 
>> diff --git a/include/linux/netlink.h b/include/linux/netlink.h
>> index d73cfe5b6bc2..0db4ffe6186b 100644
>> --- a/include/linux/netlink.h
>> +++ b/include/linux/netlink.h
>> @@ -50,6 +50,7 @@ struct netlink_kernel_cfg {
>> 	struct mutex	*cb_mutex;
>> 	int		(*bind)(struct net *net, int group);
>> 	void		(*unbind)(struct net *net, int group);
>> +	void (*release) (struct sock *sk, unsigned long *groups);
>> };
>> 
>> struct sock *__netlink_kernel_create(struct net *net, int unit,
>> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
>> index e75e5156e4ac..383c10c6e6e3 100644
>> --- a/net/netlink/af_netlink.c
>> +++ b/net/netlink/af_netlink.c
>> @@ -677,6 +677,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
>> 	struct netlink_sock *nlk;
>> 	int (*bind)(struct net *net, int group);
>> 	void (*unbind)(struct net *net, int group);
>> +	void (*release)(struct sock *sock, unsigned long *groups);
>> 	int err = 0;
>> 
>> 	sock->state = SS_UNCONNECTED;
>> @@ -704,6 +705,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
>> 	cb_mutex = nl_table[protocol].cb_mutex;
>> 	bind = nl_table[protocol].bind;
>> 	unbind = nl_table[protocol].unbind;
>> +	release = nl_table[protocol].release;
>> 	netlink_unlock_table();
>> 
>> 	if (err < 0)
>> @@ -719,6 +721,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
>> 	nlk->module = module;
>> 	nlk->netlink_bind = bind;
>> 	nlk->netlink_unbind = unbind;
>> +	nlk->netlink_release = release;
>> out:
>> 	return err;
>> 
>> @@ -763,6 +766,8 @@ static int netlink_release(struct socket *sock)
>> 	 * OK. Socket is unlinked, any packets that arrive now
>> 	 * will be purged.
>> 	 */
>> +	if (nlk->netlink_release)
>> +		nlk->netlink_release(sk, nlk->groups);
>> 
>> 	/* must not acquire netlink_table_lock in any way again before unbind
>> 	 * and notifying genetlink is done as otherwise it might deadlock
>> @@ -2091,6 +2096,7 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
>> 		if (cfg) {
>> 			nl_table[unit].bind = cfg->bind;
>> 			nl_table[unit].unbind = cfg->unbind;
>> +			nl_table[unit].release = cfg->release;
>> 			nl_table[unit].flags = cfg->flags;
>> 		}
>> 		nl_table[unit].registered = 1;
>> diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
>> index 90a3198a9b7f..cb2688aa347a 100644
>> --- a/net/netlink/af_netlink.h
>> +++ b/net/netlink/af_netlink.h
>> @@ -42,6 +42,8 @@ struct netlink_sock {
>> 	void			(*netlink_rcv)(struct sk_buff *skb);
>> 	int			(*netlink_bind)(struct net *net, int group);
>> 	void			(*netlink_unbind)(struct net *net, int group);
>> +	void			(*netlink_release)(struct sock *sk,
>> +						 unsigned long *groups);
>> 	struct module		*module;
>> 
>> 	struct rhash_head	node;
>> @@ -64,6 +66,8 @@ struct netlink_table {
>> 	struct module		*module;
>> 	int			(*bind)(struct net *net, int group);
>> 	void			(*unbind)(struct net *net, int group);
>> +	void (*release)(struct sock *sk, 
> 
> The line above ends in a space.
> 

Thanks, will fix in v7.

>> +					 unsigned long *groups);
>> 	int			registered;
>> };
>> 
>> -- 
>> 2.41.0