[PATCH RFC bpf-next 11/52] libbpf: factor out __bpf_set_link_xdp_fd_replace() args into a struct

[Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>]

Its argument list already consists of 4 entries, and there are more
to be added. It's convenient to add new opts as they are already
being passed using structs, but at the end the mentioned function
take all the opts one by one.
Place them into a local struct which will satisfy every initial call
site, so it will be now a matter of adding a new field and a
corresponding nlattr_add() to handle a new opt.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
---
 tools/lib/bpf/netlink.c | 60 ++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 18 deletions(-)

diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index cbc8967d5402..3a25178d0d12 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -230,8 +230,15 @@ static int libbpf_netlink_send_recv(struct libbpf_nla_req *req,
 	return ret;
 }
 
-static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
-					 __u32 flags)
+struct __bpf_set_link_xdp_fd_opts {
+	int ifindex;
+	int fd;
+	int old_fd;
+	__u32 flags;
+};
+
+static int
+__bpf_set_link_xdp_fd_replace(const struct __bpf_set_link_xdp_fd_opts *opts)
 {
 	struct nlattr *nla;
 	int ret;
@@ -242,22 +249,23 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
 	req.nh.nlmsg_flags    = NLM_F_REQUEST | NLM_F_ACK;
 	req.nh.nlmsg_type     = RTM_SETLINK;
 	req.ifinfo.ifi_family = AF_UNSPEC;
-	req.ifinfo.ifi_index  = ifindex;
+	req.ifinfo.ifi_index  = opts->ifindex;
 
 	nla = nlattr_begin_nested(&req, IFLA_XDP);
 	if (!nla)
 		return -EMSGSIZE;
-	ret = nlattr_add(&req, IFLA_XDP_FD, &fd, sizeof(fd));
+	ret = nlattr_add(&req, IFLA_XDP_FD, &opts->fd, sizeof(opts->fd));
 	if (ret < 0)
 		return ret;
-	if (flags) {
-		ret = nlattr_add(&req, IFLA_XDP_FLAGS, &flags, sizeof(flags));
+	if (opts->flags) {
+		ret = nlattr_add(&req, IFLA_XDP_FLAGS, &opts->flags,
+				 sizeof(opts->flags));
 		if (ret < 0)
 			return ret;
 	}
-	if (flags & XDP_FLAGS_REPLACE) {
-		ret = nlattr_add(&req, IFLA_XDP_EXPECTED_FD, &old_fd,
-				 sizeof(old_fd));
+	if (opts->flags & XDP_FLAGS_REPLACE) {
+		ret = nlattr_add(&req, IFLA_XDP_EXPECTED_FD, &opts->old_fd,
+				 sizeof(opts->old_fd));
 		if (ret < 0)
 			return ret;
 	}
@@ -268,18 +276,23 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
 
 int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags, const struct bpf_xdp_attach_opts *opts)
 {
-	int old_prog_fd, err;
+	struct __bpf_set_link_xdp_fd_opts sl_opts = {
+		.ifindex = ifindex,
+		.flags = flags,
+		.fd = prog_fd,
+	};
+	int err;
 
 	if (!OPTS_VALID(opts, bpf_xdp_attach_opts))
 		return libbpf_err(-EINVAL);
 
-	old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
-	if (old_prog_fd)
+	sl_opts.old_fd = OPTS_GET(opts, old_prog_fd, 0);
+	if (sl_opts.old_fd)
 		flags |= XDP_FLAGS_REPLACE;
 	else
-		old_prog_fd = -1;
+		sl_opts.old_fd = -1;
 
-	err = __bpf_set_link_xdp_fd_replace(ifindex, prog_fd, old_prog_fd, flags);
+	err = __bpf_set_link_xdp_fd_replace(&sl_opts);
 	return libbpf_err(err);
 }
 
@@ -291,25 +304,36 @@ int bpf_xdp_detach(int ifindex, __u32 flags, const struct bpf_xdp_attach_opts *o
 int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,
 			     const struct bpf_xdp_set_link_opts *opts)
 {
-	int old_fd = -1, ret;
+	struct __bpf_set_link_xdp_fd_opts sl_opts = {
+		.ifindex = ifindex,
+		.flags = flags,
+		.old_fd = -1,
+		.fd = fd,
+	};
+	int ret;
 
 	if (!OPTS_VALID(opts, bpf_xdp_set_link_opts))
 		return libbpf_err(-EINVAL);
 
 	if (OPTS_HAS(opts, old_fd)) {
-		old_fd = OPTS_GET(opts, old_fd, -1);
+		sl_opts.old_fd = OPTS_GET(opts, old_fd, -1);
 		flags |= XDP_FLAGS_REPLACE;
 	}
 
-	ret = __bpf_set_link_xdp_fd_replace(ifindex, fd, old_fd, flags);
+	ret = __bpf_set_link_xdp_fd_replace(&sl_opts);
 	return libbpf_err(ret);
 }
 
 int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 {
+	struct __bpf_set_link_xdp_fd_opts sl_opts = {
+		.ifindex = ifindex,
+		.flags = flags,
+		.fd = fd,
+	};
 	int ret;
 
-	ret = __bpf_set_link_xdp_fd_replace(ifindex, fd, 0, flags);
+	ret = __bpf_set_link_xdp_fd_replace(&sl_opts);
 	return libbpf_err(ret);
 }
 
-- 
2.36.1