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ipv4: Optimization for fib_info lookup with nexthops

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Be optimistic about re-using a fib_info when nexthop id is given and
the route does not use metrics. Avoids a memory allocation which in
most cases is expected to be freed anyways.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Ahern 2019-06-08 14:53:33 -07:00 committed by David S. Miller
parent 493ced1ac4
commit 6c48ea5fe6
1 changed files with 65 additions and 6 deletions
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71
net/ipv4/fib_semantics.c
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@ -325,14 +325,32 @@ static inline unsigned int fib_devindex_hashfn(unsigned int val)
(val >> (DEVINDEX_HASHBITS * 2))) & mask;
}
static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
u32 prefsrc, u32 priority)
{
unsigned int val = init_val;
val ^= (protocol << 8) | scope;
val ^= prefsrc;
val ^= priority;
return val;
}
static unsigned int fib_info_hashfn_result(unsigned int val)
{
unsigned int mask = (fib_info_hash_size - 1);
unsigned int val = fi->fib_nhs;
val ^= (fi->fib_protocol << 8) | fi->fib_scope;
val ^= (__force u32)fi->fib_prefsrc;
val ^= fi->fib_priority;
return (val ^ (val >> 7) ^ (val >> 12)) & mask;
}
static inline unsigned int fib_info_hashfn(struct fib_info *fi)
{
unsigned int val;
val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
fi->fib_scope, (__force u32)fi->fib_prefsrc,
fi->fib_priority);
if (fi->nh) {
val ^= fib_devindex_hashfn(fi->nh->id);
@ -342,7 +360,40 @@ static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
} endfor_nexthops(fi)
}
return (val ^ (val >> 7) ^ (val >> 12)) & mask;
return fib_info_hashfn_result(val);
}
/* no metrics, only nexthop id */
static struct fib_info *fib_find_info_nh(struct net *net,
const struct fib_config *cfg)
{
struct hlist_head *head;
struct fib_info *fi;
unsigned int hash;
hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
cfg->fc_protocol, cfg->fc_scope,
(__force u32)cfg->fc_prefsrc,
cfg->fc_priority);
hash = fib_info_hashfn_result(hash);
head = &fib_info_hash[hash];
hlist_for_each_entry(fi, head, fib_hash) {
if (!net_eq(fi->fib_net, net))
continue;
if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
continue;
if (cfg->fc_protocol == fi->fib_protocol &&
cfg->fc_scope == fi->fib_scope &&
cfg->fc_prefsrc == fi->fib_prefsrc &&
cfg->fc_priority == fi->fib_priority &&
cfg->fc_type == fi->fib_type &&
cfg->fc_table == fi->fib_tb_id &&
!((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
return fi;
}
return NULL;
}
static struct fib_info *fib_find_info(struct fib_info *nfi)
@ -1309,6 +1360,14 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
}
if (cfg->fc_nh_id) {
if (!cfg->fc_mx) {
fi = fib_find_info_nh(net, cfg);
if (fi) {
fi->fib_treeref++;
return fi;
}
}
nh = nexthop_find_by_id(net, cfg->fc_nh_id);
if (!nh) {
NL_SET_ERR_MSG(extack, "Nexthop id does not exist");