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Commit 6c48ea5f authored by David Ahern's avatar David Ahern Committed by David S. Miller
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ipv4: Optimization for fib_info lookup with nexthops 



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: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 493ced1a

net/ipv4/fib_semantics.c

+65 −6
Original line number Diff line number Diff line
@@ -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");