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ipv4: remove fib_info_devhash[]

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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: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241004134720.579244-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-10-04 13:47:20 +00:00 committed by Jakub Kicinski
parent 143ca845ec
commit a3f5f4c2f9
3 changed files with 19 additions and 20 deletions
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1
Documentation/networking/net_cachelines/net_device.rst
View File

@ -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

3
include/linux/netdevice.h
View File

@ -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

35
net/ipv4/fib_semantics.c
View File

@ -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)
}
@ -1948,12 +1941,12 @@ 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)
fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
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;