Re: [PATCH v3 1/4] networking: Remove the now superfluous sentinel elements from ctl_table array

On Mon, Apr 15, 2024 at 04:12:10PM -0700, Kuniyuki Iwashima wrote:
> From: Joel Granados via B4 Relay <[email protected]>
> Date: Fri, 12 Apr 2024 16:48:29 +0200
> > From: Joel Granados <[email protected]>
...
> > Signed-off-by: Joel Granados <[email protected]>
> > ---
> >  net/core/neighbour.c                | 5 +----
> >  net/core/sysctl_net_core.c          | 9 ++++-----
> >  net/dccp/sysctl.c                   | 2 --
> >  net/ieee802154/6lowpan/reassembly.c | 6 +-----
> >  net/ipv4/devinet.c                  | 5 ++---
> >  net/ipv4/ip_fragment.c              | 2 --
> >  net/ipv4/route.c                    | 8 ++------
> >  net/ipv4/sysctl_net_ipv4.c          | 7 +++----
> >  net/ipv4/xfrm4_policy.c             | 1 -
> >  net/ipv6/addrconf.c                 | 5 +----
> >  net/ipv6/icmp.c                     | 1 -
> >  net/ipv6/reassembly.c               | 2 --
> >  net/ipv6/route.c                    | 5 -----
> >  net/ipv6/sysctl_net_ipv6.c          | 4 +---
> >  net/ipv6/xfrm6_policy.c             | 1 -
> >  net/llc/sysctl_net_llc.c            | 8 ++------
> >  net/mpls/af_mpls.c                  | 3 +--
> >  net/mptcp/ctrl.c                    | 1 -
> >  net/netrom/sysctl_net_netrom.c      | 1 -
> >  net/phonet/sysctl.c                 | 1 -
> >  net/rds/ib_sysctl.c                 | 1 -
> >  net/rds/sysctl.c                    | 1 -
> >  net/rds/tcp.c                       | 1 -
> >  net/rose/sysctl_net_rose.c          | 1 -
> >  net/rxrpc/sysctl.c                  | 1 -
> >  net/sctp/sysctl.c                   | 6 +-----
> >  net/smc/smc_sysctl.c                | 1 -
> >  net/sunrpc/sysctl.c                 | 1 -
> >  net/sunrpc/xprtrdma/svc_rdma.c      | 1 -
> >  net/sunrpc/xprtrdma/transport.c     | 1 -
> >  net/sunrpc/xprtsock.c               | 1 -
> >  net/tipc/sysctl.c                   | 1 -
> >  net/unix/sysctl_net_unix.c          | 1 -
> >  net/x25/sysctl_net_x25.c            | 1 -
> >  net/xfrm/xfrm_sysctl.c              | 5 +----
> >  35 files changed, 20 insertions(+), 81 deletions(-)
> 
> You may want to split patch based on subsystem or the type of changes
> to make review easier.

That is fair. It is a big chunk:). I'll put the trivial patches together
to avoid having an 18 commits to instead have 8. This is my proposal
based on MAINTAINERS file:

### Not in MAINTAINERS / Orphaned
net/core/neighbour.c
net/core/sysctl_net_core.c
net/ieee802154/6lowpan/reassembly.c
net/mpls/af_mpls.c
net/unix/sysctl_net_unix.c
net/dccp/sysctl.c

### NETWORKING
net/ipv4/devinet.c
net/ipv4/ip_fragment.c
net/ipv4/route.c
net/ipv4/sysctl_net_ipv4.c
net/ipv4/xfrm4_policy.c
net/ipv6/addrconf.c
net/ipv6/icmp.c
net/ipv6/reassembly.c
net/ipv6/route.c
net/ipv6/sysctl_net_ipv6.c
net/ipv6/xfrm6_policy.c

### RDS
net/rds/ib_sysctl.c
net/rds/sysctl.c
net/rds/tcp.c

### SUNRPC
net/sunrpc/sysctl.c
net/sunrpc/xprtrdma/svc_rdma.c
net/sunrpc/xprtrdma/transport.c
net/sunrpc/xprtsock.c

### LLC/MTCP/NETROM/PHONET/ROSE/RXRPC/SCTP/SMC/TIPC/x.25/IPSEC
net/llc/sysctl_net_llc.c
net/mptcp/ctrl.c
net/netrom/sysctl_net_netrom.c
net/phonet/sysctl.c
net/rose/sysctl_net_rose.c
net/rxrpc/sysctl.c
net/sctp/sysctl.c
net/smc/smc_sysctl.c
net/tipc/sysctl.c
net/x25/sysctl_net_x25.c
net/xfrm/xfrm_sysctl.c

> 
> 
> > 
> > diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> > index 552719c3bbc3..b0327402b3e6 100644
> > --- a/net/core/neighbour.c
> > +++ b/net/core/neighbour.c
> > @@ -3728,7 +3728,7 @@ static int neigh_proc_base_reachable_time(struct ctl_table *ctl, int write,
> >  
> >  static struct neigh_sysctl_table {
> >  	struct ctl_table_header *sysctl_header;
> > -	struct ctl_table neigh_vars[NEIGH_VAR_MAX + 1];
> > +	struct ctl_table neigh_vars[NEIGH_VAR_MAX];
> >  } neigh_sysctl_template __read_mostly = {
> >  	.neigh_vars = {
> >  		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(MCAST_PROBES, "mcast_solicit"),
> > @@ -3779,7 +3779,6 @@ static struct neigh_sysctl_table {
> >  			.extra2		= SYSCTL_INT_MAX,
> >  			.proc_handler	= proc_dointvec_minmax,
> >  		},
> > -		{},
> >  	},
> >  };
> >  
> > @@ -3807,8 +3806,6 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
> >  	if (dev) {
> >  		dev_name_source = dev->name;
> >  		/* Terminate the table early */
> 
> You can remove this comment.
Why? I do not think we should remove it because it is what the change to
neigh_vars_size is doing.

> 
> 
> > -		memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
> > -		       sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
> >  		neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS + 1;
> >  	} else {
> >  		struct neigh_table *tbl = p->tbl;
> > diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
> > index 6973dda3abda..46f5143e86be 100644
> > --- a/net/core/sysctl_net_core.c
> > +++ b/net/core/sysctl_net_core.c
> > @@ -660,7 +660,6 @@ static struct ctl_table net_core_table[] = {
> >  		.proc_handler	= proc_dointvec_minmax,
> >  		.extra1		= SYSCTL_ZERO,
> >  	},
> > -	{ }
> >  };
> >  
> >  static struct ctl_table netns_core_table[] = {
> > @@ -697,7 +696,6 @@ static struct ctl_table netns_core_table[] = {
> >  		.extra2		= SYSCTL_ONE,
> >  		.proc_handler	= proc_dou8vec_minmax,
> >  	},
> > -	{ }
> >  };
> >  
> >  static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
> > @@ -715,7 +713,8 @@ __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
> >  
> >  static __net_init int sysctl_core_net_init(struct net *net)
> >  {
> > -	struct ctl_table *tbl, *tmp;
> > +	struct ctl_table *tbl;
> > +	size_t table_size = ARRAY_SIZE(netns_core_table);
> 
> When you add a new variable, please keep reverse xmas tree.
Thx for pointing this out. Was not aware of this quirk in net code. Will
include it for my next version.

> 
> Also, you can reuse this variable for the following
> register_net_sysctl_sz(), but it's inconsistent in the
> this patch..
> 
>   table_size
>   * sysctl_route_net_init
>   * ipv4_sysctl_init_net
> 
>   ARRAY_SIZE
>   * __addrconf_sysctl_register
>   * ipv6_sysctl_net_init
>   * mpls_dev_sysctl_register
>   * sctp_sysctl_net_register
> 
> 
> >  
> >  	tbl = netns_core_table;
> >  	if (!net_eq(net, &init_net)) {
> > @@ -723,8 +722,8 @@ static __net_init int sysctl_core_net_init(struct net *net)
> >  		if (tbl == NULL)
> >  			goto err_dup;
> >  
> > -		for (tmp = tbl; tmp->procname; tmp++)
> > -			tmp->data += (char *)net - (char *)&init_net;
> > +		for (int i = 0; i < table_size; ++i)
> >  	.devinet_vars = {
...
> >  		.extra1		= SYSCTL_ONE,
> >  	},
> > -	{ }
> >  };
> >  
> >  static __net_init int ipv4_sysctl_init_net(struct net *net)
> >  {
> >  	struct ctl_table *table;
> > +	size_t table_size = ARRAY_SIZE(ipv4_net_table);
> 
> nit: keep reverse xmax tree order.
Ok.

> 
> 
> >  
> >  	table = ipv4_net_table;
> >  	if (!net_eq(net, &init_net)) {
> > @@ -1517,7 +1516,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
> >  		if (!table)
> >  			goto err_alloc;
> >  
> > -		for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) {
...
> >  
> >  static int __addrconf_sysctl_register(struct net *net, char *dev_name,
> > @@ -7197,7 +7194,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
> >  	if (!table)
> >  		goto out;
> >  
> > -	for (i = 0; table[i].data; i++) {
> > +	for (i = 0; i < ARRAY_SIZE(addrconf_sysctl); i++) {
> 
>                         ^^^
Did you mean reuse variable here? What does this mean?

> 
> 
> >  		table[i].data += (char *)p - (char *)&ipv6_devconf;
> >  		/* If one of these is already set, then it is not safe to
> >  		 * overwrite either of them: this makes proc_dointvec_minmax
> > diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
> > index 1635da07285f..91cbf8e8009f 100644
> > --- a/net/ipv6/icmp.c
> > +++ b/net/ipv6/icmp.c
> > @@ -1206,7 +1206,6 @@ static struct ctl_table ipv6_icmp_table_template[] = {
> >  		.extra1		= SYSCTL_ZERO,
...
> > -	{ }
> >  };
> >  
> >  static int __net_init ipv6_sysctl_net_init(struct net *net)
> > @@ -264,7 +262,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
> >  	if (!ipv6_table)
> >  		goto out;
> >  	/* Update the variables to point into the current struct net */
> > -	for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
> > +	for (i = 0; i < ARRAY_SIZE(ipv6_table_template); i++)
> 
>                         ^^^
Did you mean reuse variable here? What does this mean?
> 
> 
> >  		ipv6_table[i].data += (void *)net - (void *)&init_net;
> >  
> >  	ipv6_route_table = ipv6_route_sysctl_init(net);
> > diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
> > index 42fb6996b077..499b5f5c19fc 100644
> > --- a/net/ipv6/xfrm6_policy.c
> > +++ b/net/ipv6/xfrm6_policy.c
> > @@ -184,7 +184,6 @@ static struct ctl_table xfrm6_policy_table[] = {
> >  		.mode		= 0644,
> >  		.proc_handler   = proc_dointvec,
> >  	},
> > -	{ }
> >  };
> >  
> >  static int __net_init xfrm6_net_sysctl_init(struct net *net)
> > diff --git a/net/llc/sysctl_net_llc.c b/net/llc/sysctl_net_llc.c
> > index 8443a6d841b0..72e101135f8c 100644
> > --- a/net/llc/sysctl_net_llc.c
> > +++ b/net/llc/sysctl_net_llc.c
> > @@ -44,11 +44,6 @@ static struct ctl_table llc2_timeout_table[] = {
> >  		.mode		= 0644,
> >  		.proc_handler   = proc_dointvec_jiffies,
> >  	},
> > -	{ },
> > -};
> > -
> > -static struct ctl_table llc_station_table[] = {
> > -	{ },
> >  };
> >  
> >  static struct ctl_table_header *llc2_timeout_header;
> > @@ -56,8 +51,9 @@ static struct ctl_table_header *llc_station_header;
> >  
> >  int __init llc_sysctl_init(void)
> >  {
> > +	struct ctl_table empty[1] = {};
> >  	llc2_timeout_header = register_net_sysctl(&init_net, "net/llc/llc2/timeout", llc2_timeout_table);
> > -	llc_station_header = register_net_sysctl(&init_net, "net/llc/station", llc_station_table);
> > +	llc_station_header = register_net_sysctl_sz(&init_net, "net/llc/station", empty, 0);
> 
> Do we really need this ... ??
That is a good question, but its something that needs to be address
outside this patchset. I'm just keeping current behaviour.

> 
> 
> >  
> >  	if (!llc2_timeout_header || !llc_station_header) {
> >  		llc_sysctl_exit();
> > diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
> > index 6dab883a08dd..e163fac55ffa 100644
> > --- a/net/mpls/af_mpls.c
> > +++ b/net/mpls/af_mpls.c
> > @@ -1393,7 +1393,6 @@ static const struct ctl_table mpls_dev_table[] = {
> >  		.proc_handler	= mpls_conf_proc,
> >  		.data		= MPLS_PERDEV_SYSCTL_OFFSET(input_enabled),
> >  	},
> > -	{ }
> >  };
> >  
> >  static int mpls_dev_sysctl_register(struct net_device *dev,
> > @@ -2689,7 +2688,7 @@ static int mpls_net_init(struct net *net)
> >  	/* Table data contains only offsets relative to the base of
> >  	 * the mdev at this point, so make them absolute.
> >  	 */
> > -	for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
> > +	for (i = 0; i < ARRAY_SIZE(mpls_table); i++)
> 
>                         ^^^
> 
> 
> >  		table[i].data = (char *)net + (uintptr_t)table[i].data;
> >  
> >  	net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
> > diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
> > index 13fe0748dde8..8bf7c26a0878 100644
> > --- a/net/mptcp/ctrl.c
> > +++ b/net/mptcp/ctrl.c
...
> >  
> >  	net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
> >  						      table_size);
> > 
> > -- 
> > 2.43.0
> B

Thx for the review

Best
-- 

Joel Granados

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