netdev - [PATCHv3 net 1/2] fib: convert fib_nh_is_v6 and nh

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Date: Thu, 21 Sep 2023 11:14:08 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Ido Schimmel <idosch@...dia.com>,
	David Ahern <dsahern@...nel.org>,
	Benjamin Poirier <bpoirier@...dia.com>,
	Thomas Haller <thaller@...hat.com>,
	Stephen Hemminger <stephen@...workplumber.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Nicolas Dichtel <nicolas.dichtel@...nd.com>,
	Hangbin Liu <liuhangbin@...il.com>,
	Ido Schimmel <idosch@...sch.org>
Subject: [PATCHv3 net 1/2] fib: convert fib_nh_is_v6 and nh_updated to use a single bit

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@...sch.org>
Signed-off-by: Hangbin Liu <liuhangbin@...il.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 f0c13864180e..6d05469cf5da 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 eafa4a033515..b2858b0a1229 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1573,7 +1573,7 @@ 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 bbff68b5b5d4..54ba53c89b3d 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)
-- 
2.41.0