[RTNL]: Message handler registration interface
This patch adds a new interface to register rtnetlink message
handlers replacing the exported rtnl_links[] array which
required many message handlers to be exported unnecessarly.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 33ea8ea..fb1630d 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -50,12 +50,18 @@
#include <net/sock.h>
#include <net/pkt_sched.h>
#include <net/fib_rules.h>
-#include <net/netlink.h>
+#include <net/rtnetlink.h>
#ifdef CONFIG_NET_WIRELESS_RTNETLINK
#include <linux/wireless.h>
#include <net/iw_handler.h>
#endif /* CONFIG_NET_WIRELESS_RTNETLINK */
+struct rtnl_link
+{
+ rtnl_doit_func doit;
+ rtnl_dumpit_func dumpit;
+};
+
static DEFINE_MUTEX(rtnl_mutex);
static struct sock *rtnl;
@@ -95,7 +101,151 @@
return 0;
}
-struct rtnetlink_link * rtnetlink_links[NPROTO];
+struct rtnl_link *rtnl_msg_handlers[NPROTO];
+
+static inline int rtm_msgindex(int msgtype)
+{
+ int msgindex = msgtype - RTM_BASE;
+
+ /*
+ * msgindex < 0 implies someone tried to register a netlink
+ * control code. msgindex >= RTM_NR_MSGTYPES may indicate that
+ * the message type has not been added to linux/rtnetlink.h
+ */
+ BUG_ON(msgindex < 0 || msgindex >= RTM_NR_MSGTYPES);
+
+ return msgindex;
+}
+
+static rtnl_doit_func rtnl_get_doit(int protocol, int msgindex)
+{
+ struct rtnl_link *tab;
+
+ tab = rtnl_msg_handlers[protocol];
+ if (tab == NULL || tab->doit == NULL)
+ tab = rtnl_msg_handlers[PF_UNSPEC];
+
+ return tab ? tab->doit : NULL;
+}
+
+static rtnl_dumpit_func rtnl_get_dumpit(int protocol, int msgindex)
+{
+ struct rtnl_link *tab;
+
+ tab = rtnl_msg_handlers[protocol];
+ if (tab == NULL || tab->dumpit == NULL)
+ tab = rtnl_msg_handlers[PF_UNSPEC];
+
+ return tab ? tab->dumpit : NULL;
+}
+
+/**
+ * __rtnl_register - Register a rtnetlink message type
+ * @protocol: Protocol family or PF_UNSPEC
+ * @msgtype: rtnetlink message type
+ * @doit: Function pointer called for each request message
+ * @dumpit: Function pointer called for each dump request (NLM_F_DUMP) message
+ *
+ * Registers the specified function pointers (at least one of them has
+ * to be non-NULL) to be called whenever a request message for the
+ * specified protocol family and message type is received.
+ *
+ * The special protocol family PF_UNSPEC may be used to define fallback
+ * function pointers for the case when no entry for the specific protocol
+ * family exists.
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int __rtnl_register(int protocol, int msgtype,
+ rtnl_doit_func doit, rtnl_dumpit_func dumpit)
+{
+ struct rtnl_link *tab;
+ int msgindex;
+
+ BUG_ON(protocol < 0 || protocol >= NPROTO);
+ msgindex = rtm_msgindex(msgtype);
+
+ tab = rtnl_msg_handlers[protocol];
+ if (tab == NULL) {
+ tab = kcalloc(RTM_NR_MSGTYPES, sizeof(*tab), GFP_KERNEL);
+ if (tab == NULL)
+ return -ENOBUFS;
+
+ rtnl_msg_handlers[protocol] = tab;
+ }
+
+ if (doit)
+ tab[msgindex].doit = doit;
+
+ if (dumpit)
+ tab[msgindex].dumpit = dumpit;
+
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(__rtnl_register);
+
+/**
+ * rtnl_register - Register a rtnetlink message type
+ *
+ * Identical to __rtnl_register() but panics on failure. This is useful
+ * as failure of this function is very unlikely, it can only happen due
+ * to lack of memory when allocating the chain to store all message
+ * handlers for a protocol. Meant for use in init functions where lack
+ * of memory implies no sense in continueing.
+ */
+void rtnl_register(int protocol, int msgtype,
+ rtnl_doit_func doit, rtnl_dumpit_func dumpit)
+{
+ if (__rtnl_register(protocol, msgtype, doit, dumpit) < 0)
+ panic("Unable to register rtnetlink message handler, "
+ "protocol = %d, message type = %d\n",
+ protocol, msgtype);
+}
+
+EXPORT_SYMBOL_GPL(rtnl_register);
+
+/**
+ * rtnl_unregister - Unregister a rtnetlink message type
+ * @protocol: Protocol family or PF_UNSPEC
+ * @msgtype: rtnetlink message type
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int rtnl_unregister(int protocol, int msgtype)
+{
+ int msgindex;
+
+ BUG_ON(protocol < 0 || protocol >= NPROTO);
+ msgindex = rtm_msgindex(msgtype);
+
+ if (rtnl_msg_handlers[protocol] == NULL)
+ return -ENOENT;
+
+ rtnl_msg_handlers[protocol][msgindex].doit = NULL;
+ rtnl_msg_handlers[protocol][msgindex].dumpit = NULL;
+
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(rtnl_unregister);
+
+/**
+ * rtnl_unregister_all - Unregister all rtnetlink message type of a protocol
+ * @protocol : Protocol family or PF_UNSPEC
+ *
+ * Identical to calling rtnl_unregster() for all registered message types
+ * of a certain protocol family.
+ */
+void rtnl_unregister_all(int protocol)
+{
+ BUG_ON(protocol < 0 || protocol >= NPROTO);
+
+ kfree(rtnl_msg_handlers[protocol]);
+ rtnl_msg_handlers[protocol] = NULL;
+}
+
+EXPORT_SYMBOL_GPL(rtnl_unregister_all);
static const int rtm_min[RTM_NR_FAMILIES] =
{
@@ -648,7 +798,7 @@
return err;
}
-static int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
+int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
{
int idx;
int s_idx = cb->family;
@@ -659,12 +809,12 @@
int type = cb->nlh->nlmsg_type-RTM_BASE;
if (idx < s_idx || idx == PF_PACKET)
continue;
- if (rtnetlink_links[idx] == NULL ||
- rtnetlink_links[idx][type].dumpit == NULL)
+ if (rtnl_msg_handlers[idx] == NULL ||
+ rtnl_msg_handlers[idx][type].dumpit == NULL)
continue;
if (idx > s_idx)
memset(&cb->args[0], 0, sizeof(cb->args));
- if (rtnetlink_links[idx][type].dumpit(skb, cb))
+ if (rtnl_msg_handlers[idx][type].dumpit(skb, cb))
break;
}
cb->family = idx;
@@ -672,6 +822,8 @@
return skb->len;
}
+EXPORT_SYMBOL_GPL(rtnl_dump_all);
+
void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change)
{
struct sk_buff *skb;
@@ -703,8 +855,7 @@
static __inline__ int
rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, int *errp)
{
- struct rtnetlink_link *link;
- struct rtnetlink_link *link_tab;
+ rtnl_doit_func doit;
int sz_idx, kind;
int min_len;
int family;
@@ -737,11 +888,6 @@
return -1;
}
- link_tab = rtnetlink_links[family];
- if (link_tab == NULL)
- link_tab = rtnetlink_links[PF_UNSPEC];
- link = &link_tab[type];
-
sz_idx = type>>2;
kind = type&3;
@@ -751,14 +897,14 @@
}
if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {
- if (link->dumpit == NULL)
- link = &(rtnetlink_links[PF_UNSPEC][type]);
+ rtnl_dumpit_func dumpit;
- if (link->dumpit == NULL)
+ dumpit = rtnl_get_dumpit(family, type);
+ if (dumpit == NULL)
goto err_inval;
if ((*errp = netlink_dump_start(rtnl, skb, nlh,
- link->dumpit, NULL)) != 0) {
+ dumpit, NULL)) != 0) {
return -1;
}
@@ -787,11 +933,10 @@
}
}
- if (link->doit == NULL)
- link = &(rtnetlink_links[PF_UNSPEC][type]);
- if (link->doit == NULL)
+ doit = rtnl_get_doit(family, type);
+ if (doit == NULL)
goto err_inval;
- err = link->doit(skb, nlh, (void *)&rta_buf[0]);
+ err = doit(skb, nlh, (void *)&rta_buf[0]);
*errp = err;
return err;
@@ -886,7 +1031,6 @@
EXPORT_SYMBOL(__rta_fill);
EXPORT_SYMBOL(rtattr_strlcpy);
EXPORT_SYMBOL(rtattr_parse);
-EXPORT_SYMBOL(rtnetlink_links);
EXPORT_SYMBOL(rtnetlink_put_metrics);
EXPORT_SYMBOL(rtnl_lock);
EXPORT_SYMBOL(rtnl_trylock);