[PATCH] net: shrink struct net_device by #ifdef-ing protocol-specific members

[PATCH] net: shrink struct net_device by #ifdef-ing protocol-specific members

[Lucian Adrian Grijincu]

Some members of net_device are used only by some protocols.

If those protocols are not compiled (as modules or linked in) they
should not take up space in the structure.

These members are also used in inline functions defined in headers not
protected by the protocol-specific CONFIG_ guards. Adding #ifdef CONFIG_*
guards header wide is against the current style and more invasive than
guarding only the definitions.

Signed-off-by: Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
---
 include/linux/inetdevice.h |    2 ++
 include/linux/netdevice.h  |   14 ++++++++++++++
 include/net/ax25.h         |    2 ++
 net/core/dev.c             |    6 ++++++
 4 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index acef2a7..88132ff 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -166,6 +166,7 @@ static __inline__ int bad_mask(__be32 mask, __be32 addr)

 #define endfor_ifa(in_dev) }

+#ifdef CONFIG_INET
 static inline struct in_device *__in_dev_get_rcu(const struct
net_device *dev)
 {
 	struct in_device *in_dev = dev->ip_ptr;
@@ -192,6 +193,7 @@ __in_dev_get_rtnl(const struct net_device *dev)
 {
 	return (struct in_device*)dev->ip_ptr;
 }
+#endif /* CONFIG_INET */

 extern void in_dev_finish_destroy(struct in_device *idev);

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5a96a1a..d175bb9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -762,14 +762,28 @@ struct net_device
 #ifdef CONFIG_NET_DSA
 	void			*dsa_ptr;	/* dsa specific data */
 #endif
+#ifdef CONFIG_ATALK
 	void 			*atalk_ptr;	/* AppleTalk link 	*/
+#endif
+#ifdef CONFIG_INET
 	void			*ip_ptr;	/* IPv4 specific data	*/
+#endif
+#ifdef CONFIG_DECNET
 	void                    *dn_ptr;        /* DECnet specific data */
+#endif
+#ifdef CONFIG_IPV6
 	void                    *ip6_ptr;       /* IPv6 specific data */
+#endif
+#ifdef CONFIG_ECONET
 	void			*ec_ptr;	/* Econet specific data	*/
+#endif
+#ifdef CONFIG_AX25
 	void			*ax25_ptr;	/* AX.25 specific data */
+#endif
+#ifdef CONFIG_WIRELESS
 	struct wireless_dev	*ieee80211_ptr;	/* IEEE 802.11 specific data,
 						   assign before registering */
+#endif

 /*
  * Cache line mostly used on receive path (including eth_type_trans())
diff --git a/include/net/ax25.h b/include/net/ax25.h
index 717e219..5695968 100644
--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -300,10 +300,12 @@ extern void ax25_digi_invert(const ax25_digi *,
ax25_digi *);
 extern ax25_dev *ax25_dev_list;
 extern spinlock_t ax25_dev_lock;

+#ifdef CONFIG_AX25
 static inline ax25_dev *ax25_dev_ax25dev(struct net_device *dev)
 {
 	return dev->ax25_ptr;
 }
+#endif /* CONFIG_AX25 */

 extern ax25_dev *ax25_addr_ax25dev(ax25_address *);
 extern void ax25_dev_device_up(struct net_device *);
diff --git a/net/core/dev.c b/net/core/dev.c
index e2e9e4a..3171148 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4686,9 +4686,15 @@ void netdev_run_todo(void)

 		/* paranoia */
 		BUG_ON(atomic_read(&dev->refcnt));
+#ifdef CONFIG_INET
 		WARN_ON(dev->ip_ptr);
+#endif
+#ifdef CONFIG_IPV6
 		WARN_ON(dev->ip6_ptr);
+#endif
+#ifdef CONFIG_DECNET
 		WARN_ON(dev->dn_ptr);
+#endif

 		if (dev->destructor)
 			dev->destructor(dev);
-- 
1.6.3.3

Re: [PATCH] net: shrink struct net_device by #ifdef-ing protocol-specific members

[Eric Dumazet]

Lucian Adrian Grijincu a écrit :
> Some members of net_device are used only by some protocols.
> 
> If those protocols are not compiled (as modules or linked in) they
> should not take up space in the structure.
> 
> These members are also used in inline functions defined in headers not
> protected by the protocol-specific CONFIG_ guards. Adding #ifdef CONFIG_*
> guards header wide is against the current style and more invasive than
> guarding only the definitions.
> 
> Signed-off-by: Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
> ---
>  include/linux/inetdevice.h |    2 ++
>  include/linux/netdevice.h  |   14 ++++++++++++++
>  include/net/ax25.h         |    2 ++
>  net/core/dev.c             |    6 ++++++
>  4 files changed, 24 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
> index acef2a7..88132ff 100644
> --- a/include/linux/inetdevice.h
> +++ b/include/linux/inetdevice.h
> @@ -166,6 +166,7 @@ static __inline__ int bad_mask(__be32 mask, __be32 addr)
> 
>  #define endfor_ifa(in_dev) }
> 
> +#ifdef CONFIG_INET
>  static inline struct in_device *__in_dev_get_rcu(const struct
> net_device *dev)
>  {
>  	struct in_device *in_dev = dev->ip_ptr;
> @@ -192,6 +193,7 @@ __in_dev_get_rtnl(const struct net_device *dev)
>  {
>  	return (struct in_device*)dev->ip_ptr;
>  }
> +#endif /* CONFIG_INET */
> 
>  extern void in_dev_finish_destroy(struct in_device *idev);
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 5a96a1a..d175bb9 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -762,14 +762,28 @@ struct net_device
>  #ifdef CONFIG_NET_DSA
>  	void			*dsa_ptr;	/* dsa specific data */
>  #endif
> +#ifdef CONFIG_ATALK
>  	void 			*atalk_ptr;	/* AppleTalk link 	*/
> +#endif
> +#ifdef CONFIG_INET
>  	void			*ip_ptr;	/* IPv4 specific data	*/
> +#endif
> +#ifdef CONFIG_DECNET
>  	void                    *dn_ptr;        /* DECnet specific data */
> +#endif
> +#ifdef CONFIG_IPV6

I dont know if your patch will please that much.

For example, IPV6 can be a module, so you cannot only test 
ifdef CONFIG_IPV6

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)