Commit a3f5f4c2 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

ipv4: remove fib_info_devhash[] 



Upcoming per-netns RTNL conversion needs to get rid
of shared hash tables.

fib_info_devhash[] is one of them.

It is unclear why we used a hash table, because
a single hlist_head per net device was cheaper and scalable.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241004134720.579244-5-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 143ca845

Documentation/networking/net_cachelines/net_device.rst

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ unsigned_int allmulti 
bool                                uc_promisc                                                      

unsigned_char                       nested_level                                                    

struct_in_device*                   ip_ptr                  read_mostly         read_mostly         __in_dev_get

struct hlist_head                   fib_nh_head

struct_inet6_dev*                   ip6_ptr                 read_mostly         read_mostly         __in6_dev_get

struct_vlan_info*                   vlan_info                                                       

struct_dsa_port*                    dsa_ptr

include/linux/netdevice.h

+3 −0
Original line number Diff line number Diff line
@@ -2211,6 +2211,9 @@ struct net_device { 


	/* Protocol-specific pointers */

	struct in_device __rcu	*ip_ptr;

	/** @fib_nh_head: nexthops associated with this netdev */

	struct hlist_head	fib_nh_head;



#if IS_ENABLED(CONFIG_VLAN_8021Q)

	struct vlan_info __rcu	*vlan_info;

#endif

net/ipv4/fib_semantics.c

+15 −20
Original line number Diff line number Diff line
@@ -56,10 +56,6 @@ static unsigned int fib_info_hash_size; 
static unsigned int fib_info_hash_bits;

static unsigned int fib_info_cnt;



#define DEVINDEX_HASHBITS 8

#define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)

static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];



/* for_nexthops and change_nexthops only used when nexthop object

 * is not set in a fib_info. The logic within can reference fib_nh.

 */
@@ -319,12 +315,9 @@ static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi) 
	return 0;

}



static struct hlist_head *

fib_info_devhash_bucket(const struct net_device *dev)

static struct hlist_head *fib_nh_head(struct net_device *dev)

{

	u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;



	return &fib_info_devhash[hash_32(val, DEVINDEX_HASHBITS)];

	return &dev->fib_nh_head;

}



static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
@@ -435,11 +428,11 @@ int ip_fib_check_default(__be32 gw, struct net_device *dev) 
	struct hlist_head *head;

	struct fib_nh *nh;



	head = fib_info_devhash_bucket(dev);

	head = fib_nh_head(dev);



	hlist_for_each_entry_rcu(nh, head, nh_hash) {

		if (nh->fib_nh_dev == dev &&

		    nh->fib_nh_gw4 == gw &&

		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);

		if (nh->fib_nh_gw4 == gw &&

		    !(nh->fib_nh_flags & RTNH_F_DEAD)) {

			return 0;

		}
@@ -1595,7 +1588,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg, 


			if (!nexthop_nh->fib_nh_dev)

				continue;

			head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);

			head = fib_nh_head(nexthop_nh->fib_nh_dev);

			hlist_add_head_rcu(&nexthop_nh->nh_hash, head);

		} endfor_nexthops(fi)

	}
@@ -1948,11 +1941,11 @@ void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig) 


void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)

{

	struct hlist_head *head = fib_info_devhash_bucket(dev);

	struct hlist_head *head = fib_nh_head(dev);

	struct fib_nh *nh;



	hlist_for_each_entry(nh, head, nh_hash) {

		if (nh->fib_nh_dev == dev)

		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);

		fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);

	}

}
@@ -1967,7 +1960,7 @@ void fib_sync_mtu(struct net_device *dev, u32 orig_mtu) 
 */

int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)

{

	struct hlist_head *head = fib_info_devhash_bucket(dev);

	struct hlist_head *head = fib_nh_head(dev);

	struct fib_info *prev_fi = NULL;

	int scope = RT_SCOPE_NOWHERE;

	struct fib_nh *nh;
@@ -1981,7 +1974,8 @@ int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force) 
		int dead;



		BUG_ON(!fi->fib_nhs);

		if (nh->fib_nh_dev != dev || fi == prev_fi)

		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);

		if (fi == prev_fi)

			continue;

		prev_fi = fi;

		dead = 0;
@@ -2131,7 +2125,7 @@ int fib_sync_up(struct net_device *dev, unsigned char nh_flags) 
	}



	prev_fi = NULL;

	head = fib_info_devhash_bucket(dev);

	head = fib_nh_head(dev);

	ret = 0;



	hlist_for_each_entry(nh, head, nh_hash) {
@@ -2139,7 +2133,8 @@ int fib_sync_up(struct net_device *dev, unsigned char nh_flags) 
		int alive;



		BUG_ON(!fi->fib_nhs);

		if (nh->fib_nh_dev != dev || fi == prev_fi)

		DEBUG_NET_WARN_ON_ONCE(nh->fib_nh_dev != dev);

		if (fi == prev_fi)

			continue;



		prev_fi = fi;