[PATCHv2 net-next 1/2] fib: convert fib_nh_is_v6 and nh_updated to use a single bit

Hangbin Liu
2023-08-09T14:02:59Z

The FIB info structure currently looks like this:
struct fib_info {
struct hlist_node fib_hash; /* 0 16 */
[...]
u32 fib_priority; /* 80 4 */

/* XXX 4 bytes hole, try to pack */

struct dst_metrics * fib_metrics; /* 88 8 */
int fib_nhs; /* 96 4 */
bool fib_nh_is_v6; /* 100 1 */
bool nh_updated; /* 101 1 */

/* XXX 2 bytes hole, try to pack */

struct nexthop * nh; /* 104 8 */
struct callback_head rcu __attribute__((__aligned__(8))); /* 112 16 */
/* --- cacheline 2 boundary (128 bytes) --- */
struct fib_nh fib_nh[]; /* 128 0 */

/* size: 128, cachelines: 2, members: 21 */
/* sum members: 122, holes: 2, sum holes: 6 */
/* forced alignments: 1 */
} __attribute__((__aligned__(8)));

Let's convert fib_nh_is_v6 and nh_updated to use a single bit, so that
we can add other functional bits in later patch.

Suggested-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
include/net/ip_fib.h | 4 ++--
net/ipv4/fib_semantics.c | 2 +-
net/ipv4/nexthop.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index a378eff827c7..a91f8a28689a 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -152,8 +152,8 @@ struct fib_info {
#define fib_rtt fib_metrics->metrics[RTAX_RTT-1]
#define fib_advmss fib_metrics->metrics[RTAX_ADVMSS-1]
int fib_nhs;
- bool fib_nh_is_v6;
- bool nh_updated;
+ u8 fib_nh_is_v6:1,
+ nh_updated:1;
struct nexthop *nh;
struct rcu_head rcu;
struct fib_nh fib_nh[];
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 65ba18a91865..ce1c10e408cf 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1572,7 +1572,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
fi->fib_scope);
if (nexthop_nh->fib_nh_gw_family == AF_INET6)
- fi->fib_nh_is_v6 = true;
+ fi->fib_nh_is_v6 = 1;
} endfor_nexthops(fi)

fib_rebalance(fi);
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 93f14d39fef6..5243bb80bade 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -2213,12 +2213,12 @@ static void __nexthop_replace_notify(struct net *net, struct nexthop *nh,
* and then walk the fib tables once
*/
list_for_each_entry(fi, &nh->fi_list, nh_list)
- fi->nh_updated = true;
+ fi->nh_updated = 1;

fib_info_notify_update(net, info);

list_for_each_entry(fi, &nh->fi_list, nh_list)
- fi->nh_updated = false;
+ fi->nh_updated = 0;
}

list_for_each_entry(f6i, &nh->f6i_list, nh_list)
--
2.38.1