datapath: Ignore return value from rtnl_notify().

In Linux 2.6.30, the rtnl_notify() return type was changed from int to
void along with the following commit message:

    This patch also modifies the rtnetlink code to ignore the return
    value of rtnl_notify() in all callers. The function rtnl_notify()
    (before this patch) returned the error of the unicast notification
    which makes rtnl_set_sk_err() reports errors to all listeners. This
    is not of any help since the origin of the change (the socket that
    requested the echoing) notices the ENOBUFS error if the notification
    fails and should resync itself.

Thus there's no point in checking the return value, even in older versions
of the kernel, and so this commit changes our code to ignore it, even
on older kernel versions.  We also update the rtnl_notify() wrapper macros
to make the return type void on older kernel versions.

This has not been tested, just built.

Thanks to Mikio for spurring me to try building with Linux 2.6.29 and
2.6.30.

diff --git a/datapath/datapath.c b/datapath/datapath.c
index abc5599..aea8cc9 100644 (file)
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -165,7 +165,8 @@ static void dp_ifinfo_notify(int event, struct net_bridge_port *port)
                kfree_skb(skb);
                goto errout;
        }
-       err = rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
+       rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
+       return;
 errout:
        if (err < 0)
                rtnl_set_sk_err(net, RTNLGRP_LINK, err);

diff --git a/datapath/linux-2.6/compat-2.6/include/linux/rtnetlink.h b/datapath/linux-2.6/compat-2.6/include/linux/rtnetlink.h
index 8bc5156..4d7bd78 100644 (file)
--- a/datapath/linux-2.6/compat-2.6/include/linux/rtnetlink.h
+++ b/datapath/linux-2.6/compat-2.6/include/linux/rtnetlink.h
@@ -4,7 +4,7 @@
 #include_next <linux/rtnetlink.h>
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
-static inline int rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid,
+static inline void rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid,
                              u32 group, struct nlmsghdr *nlh, gfp_t flags)
 {
        BUG_ON(nlh);            /* not implemented */
@@ -12,7 +12,6 @@ static inline int rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid,
                /* errors reported via destination sk->sk_err */
                nlmsg_multicast(rtnl, skb, 0, group);
        }
-       return 0;
 }
 
 static inline void rtnl_set_sk_err(struct net *net, u32 group, int error)
@@ -20,10 +19,15 @@ static inline void rtnl_set_sk_err(struct net *net, u32 group, int error)
        netlink_set_err(rtnl, 0, group, error);
 }
 #elif LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
+/* No 'net' parameter in these versions. */
 #define rtnl_notify(skb, net, pid, group, nlh, flags) \
-       ((void) (net), rtnl_notify(skb, pid, group, nlh, flags))
+       ((void) (net), (void) rtnl_notify(skb, pid, group, nlh, flags))
 #define rtnl_set_sk_err(net, group, error) \
        ((void) (net), rtnl_set_sk_err(group, error))
-#endif /* linux kernel < 2.6.25 */
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(2,6,30)
+/* Make the return type effectively 'void' to match Linux 2.6.30+. */
+#define rtnl_notify(skb, net, pid, group, nlh, flags) \
+       ((void) rtnl_notify(skb, net, pid, group, nlh, flags))
+#endif
 
 #endif /* linux/rtnetlink.h wrapper */