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authorEric Dumazet <edumazet@google.com>2022-01-19 02:04:13 -0800
committerJakub Kicinski <kuba@kernel.org>2022-01-19 08:14:40 -0800
commit79eb15da3cd68f04b06edf73f9bbafa70a06871f (patch)
treee9ad4aa8aa2d54dcb07afe7c0b0fa3b807855d21 /net
parentd07418afea8f1d9896aaf9dc5ae47ac4f45b220c (diff)
ipv4: add net_hash_mix() dispersion to fib_info_laddrhash keys
net/ipv4/fib_semantics.c uses a hash table (fib_info_laddrhash) in which fib_sync_down_addr() can locate fib_info based on IPv4 local address. This hash table is resized based on total number of hashed fib_info, but the hash function is only using the local address. For hosts having many active network namespaces, all fib_info for loopback devices (IPv4 address 127.0.0.1) are hashed into a single bucket, making netns dismantles very slow. Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/fib_semantics.c29
1 files changed, 15 insertions, 14 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 9813949da104..b4589861b84c 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -52,6 +52,7 @@ static DEFINE_SPINLOCK(fib_info_lock);
static struct hlist_head *fib_info_hash;
static struct hlist_head *fib_info_laddrhash;
static unsigned int fib_info_hash_size;
+static unsigned int fib_info_hash_bits;
static unsigned int fib_info_cnt;
#define DEVINDEX_HASHBITS 8
@@ -1247,13 +1248,13 @@ int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
return err;
}
-static inline unsigned int fib_laddr_hashfn(__be32 val)
+static struct hlist_head *
+fib_info_laddrhash_bucket(const struct net *net, __be32 val)
{
- unsigned int mask = (fib_info_hash_size - 1);
+ u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
+ fib_info_hash_bits);
- return ((__force u32)val ^
- ((__force u32)val >> 7) ^
- ((__force u32)val >> 14)) & mask;
+ return &fib_info_laddrhash[slot];
}
static struct hlist_head *fib_info_hash_alloc(int bytes)
@@ -1289,6 +1290,7 @@ static void fib_info_hash_move(struct hlist_head *new_info_hash,
old_info_hash = fib_info_hash;
old_laddrhash = fib_info_laddrhash;
fib_info_hash_size = new_size;
+ fib_info_hash_bits = ilog2(new_size);
for (i = 0; i < old_size; i++) {
struct hlist_head *head = &fib_info_hash[i];
@@ -1306,21 +1308,20 @@ static void fib_info_hash_move(struct hlist_head *new_info_hash,
}
fib_info_hash = new_info_hash;
+ fib_info_laddrhash = new_laddrhash;
for (i = 0; i < old_size; i++) {
- struct hlist_head *lhead = &fib_info_laddrhash[i];
+ struct hlist_head *lhead = &old_laddrhash[i];
struct hlist_node *n;
struct fib_info *fi;
hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
struct hlist_head *ldest;
- unsigned int new_hash;
- new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
- ldest = &new_laddrhash[new_hash];
+ ldest = fib_info_laddrhash_bucket(fi->fib_net,
+ fi->fib_prefsrc);
hlist_add_head(&fi->fib_lhash, ldest);
}
}
- fib_info_laddrhash = new_laddrhash;
spin_unlock_bh(&fib_info_lock);
@@ -1605,7 +1606,7 @@ link_it:
if (fi->fib_prefsrc) {
struct hlist_head *head;
- head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
+ head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
hlist_add_head(&fi->fib_lhash, head);
}
if (fi->nh) {
@@ -1877,16 +1878,16 @@ nla_put_failure:
*/
int fib_sync_down_addr(struct net_device *dev, __be32 local)
{
- int ret = 0;
- unsigned int hash = fib_laddr_hashfn(local);
- struct hlist_head *head = &fib_info_laddrhash[hash];
int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
struct net *net = dev_net(dev);
+ struct hlist_head *head;
struct fib_info *fi;
+ int ret = 0;
if (!fib_info_laddrhash || local == 0)
return 0;
+ head = fib_info_laddrhash_bucket(net, local);
hlist_for_each_entry(fi, head, fib_lhash) {
if (!net_eq(fi->fib_net, net) ||
fi->fib_tb_id != tb_id)