ARM: 9480/1: entry: expand comment in __switch_tografted

As per discussion between the developers in the mail thread
linked, expand the comment in __switch_to so that readers
of the code understand what is going on.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 33 insertions, 0 deletions

diff --git a/net/ipv4/netlink.c b/net/ipv4/netlink.c
new file mode 100644
index 000000000..b920e1bdc
--- /dev/null
+++ b/net/ipv4/netlink.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/types.h>
+#include <net/net_namespace.h>
+#include <net/netlink.h>
+#include <linux/in6.h>
+#include <net/ip.h>
+
+int rtm_getroute_parse_ip_proto(struct nlattr *attr, u8 *ip_proto, u8 family,
+				struct netlink_ext_ack *extack)
+{
+	*ip_proto = nla_get_u8(attr);
+
+	switch (*ip_proto) {
+	case IPPROTO_TCP:
+	case IPPROTO_UDP:
+		return 0;
+	case IPPROTO_ICMP:
+		if (family != AF_INET)
+			break;
+		return 0;
+#if IS_ENABLED(CONFIG_IPV6)
+	case IPPROTO_ICMPV6:
+		if (family != AF_INET6)
+			break;
+		return 0;
+#endif
+	}
+	NL_SET_ERR_MSG(extack, "Unsupported ip proto");
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(rtm_getroute_parse_ip_proto);