From: Jakub Kicinski <kuba@kernel.org>
Date: Thu, 5 Jan 2023 04:05:21 +0000 (-0800)
Subject: netlink: add macro for checking dump ctx size
X-Git-Tag: io_uring-6.3-2023-03-03~13^2~332^2~10
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=2c7bc10d0f7b0f66d9042ed88bb3ecd588352a00;p=linux-2.6-block.git

netlink: add macro for checking dump ctx size

We encourage casting struct netlink_callback::ctx to a local
struct (in a comment above the field). Provide a convenience
macro for checking if the local struct fits into the ctx.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index d81bde5a5844..38f6334f408c 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -263,6 +263,10 @@ struct netlink_callback {
 	};
 };
 
+#define NL_ASSET_DUMP_CTX_FITS(type_name)				\
+	BUILD_BUG_ON(sizeof(type_name) >				\
+		     sizeof_field(struct netlink_callback, ctx))
+
 struct netlink_notify {
 	struct net *net;
 	u32 portid;
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 1286ae7d4609..90672e293e57 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -3866,7 +3866,7 @@ static int __init ctnetlink_init(void)
 {
 	int ret;
 
-	BUILD_BUG_ON(sizeof(struct ctnetlink_list_dump_ctx) > sizeof_field(struct netlink_callback, ctx));
+	NL_ASSET_DUMP_CTX_FITS(struct ctnetlink_list_dump_ctx);
 
 	ret = nfnetlink_subsys_register(&ctnl_subsys);
 	if (ret < 0) {