netdev - [PATCH net-next 1/7] ipv4: nexthop: Reduce allocation size of 'struct nh

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Message-Id: <20200826164857.1029764-2-idosch@idosch.org>
Date:   Wed, 26 Aug 2020 19:48:51 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, dsahern@...il.com,
        mlxsw@...dia.com, Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net-next 1/7] ipv4: nexthop: Reduce allocation size of 'struct nh_group'

From: Ido Schimmel <idosch@...dia.com>

The struct looks as follows:

struct nh_group {
	struct nh_group		*spare; /* spare group for removals */
	u16			num_nh;
	bool			mpath;
	bool			fdb_nh;
	bool			has_v4;
	struct nh_grp_entry	nh_entries[];
};

But its offset within 'struct nexthop' is also taken into account to
determine the allocation size.

Instead, use struct_size() to allocate only the required number of
bytes.

Signed-off-by: Ido Schimmel <idosch@...dia.com>
---
 net/ipv4/nexthop.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 134e92382275..d13730ff9aeb 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -133,12 +133,9 @@ static struct nexthop *nexthop_alloc(void)
 
 static struct nh_group *nexthop_grp_alloc(u16 num_nh)
 {
-	size_t sz = offsetof(struct nexthop, nh_grp)
-		    + sizeof(struct nh_group)
-		    + sizeof(struct nh_grp_entry) * num_nh;
 	struct nh_group *nhg;
 
-	nhg = kzalloc(sz, GFP_KERNEL);
+	nhg = kzalloc(struct_size(nhg, nh_entries, num_nh), GFP_KERNEL);
 	if (nhg)
 		nhg->num_nh = num_nh;
 
-- 
2.26.2