net: Make userland include of netlink.h more sane.

Currently userland will barf when including linux/netlink.h unless it
precisely includes sys/socket.h first.  The issue is where the
definition of "sa_family_t" comes from.

We've been back and forth on how to fix this issue in the past, see:

http://thread.gmane.org/gmane.linux.debian.devel.bugs.general/622621
http://thread.gmane.org/gmane.linux.network/143380

Ben Hutchings suggested we take a hint from how we handle the
sockaddr_storage type.  First we define a "__kernel_sa_family_t"
to linux/socket.h that is always defined.

Then if __KERNEL__ is defined, we also define "sa_family_t" as
equal to "__kernel_sa_family_t".

Then in places like linux/netlink.h we use __kernel_sa_family_t
in user visible datastructures.

Reported-by: Michel Machado <michel@digirati.com.br>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 2e17c5d..180540a 100644 (file)
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -29,7 +29,7 @@
 #define MAX_LINKS 32           
 
 struct sockaddr_nl {
-       sa_family_t     nl_family;      /* AF_NETLINK   */
+       __kernel_sa_family_t    nl_family;      /* AF_NETLINK   */
        unsigned short  nl_pad;         /* zero         */
        __u32           nl_pid;         /* port ID      */
                __u32           nl_groups;      /* multicast groups mask */

diff --git a/include/linux/socket.h b/include/linux/socket.h
index e17f822..d0e77f6 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -8,8 +8,10 @@
 #define _K_SS_ALIGNSIZE        (__alignof__ (struct sockaddr *))
                                /* Implementation specific desired alignment */
 
+typedef unsigned short __kernel_sa_family_t;
+
 struct __kernel_sockaddr_storage {
-       unsigned short  ss_family;              /* address family */
+       __kernel_sa_family_t    ss_family;              /* address family */
        /* Following field(s) are implementation specific */
        char            __data[_K_SS_MAXSIZE - sizeof(unsigned short)];
                                /* space to achieve desired size, */
@@ -35,7 +37,7 @@ struct seq_file;
 extern void socket_seq_show(struct seq_file *seq);
 #endif
 
-typedef unsigned short sa_family_t;
+typedef __kernel_sa_family_t   sa_family_t;
 
 /*
  *     1003.1g requires sa_family_t and that sa_data is char.