[L2TP]: Changes to existing ppp and socket kernel headers for L2TP

Add struct sockaddr_pppol2tp to carry L2TP-specific address
information for the PPPoX (PPPoL2TP) socket. Unfortunately we can't
use the union inside struct sockaddr_pppox because the L2TP-specific
data is larger than the current size of the union and we must preserve
the size of struct sockaddr_pppox for binary compatibility.

Also add a PPPIOCGL2TPSTATS ioctl to allow userspace to obtain
L2TP counters and state from the kernel.

Add new if_pppol2tp.h header.

[ Modified to use aligned_u64 in statistics structure -DaveM ]

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_ppp.h b/include/linux/if_ppp.h
index 768372f..0f2f70d 100644
--- a/include/linux/if_ppp.h
+++ b/include/linux/if_ppp.h
@@ -110,6 +110,21 @@
 	struct ppp_comp_stats stats;
 };
 
+/* For PPPIOCGL2TPSTATS */
+struct pppol2tp_ioc_stats {
+	__u16		tunnel_id;	/* redundant */
+	__u16		session_id;	/* if zero, get tunnel stats */
+	__u32		using_ipsec:1;	/* valid only for session_id == 0 */
+	aligned_u64	tx_packets;
+	aligned_u64	tx_bytes;
+	aligned_u64	tx_errors;
+	aligned_u64	rx_packets;
+	aligned_u64	rx_bytes;
+	aligned_u64	rx_seq_discards;
+	aligned_u64	rx_oos_packets;
+	aligned_u64	rx_errors;
+};
+
 #define ifr__name       b.ifr_ifrn.ifrn_name
 #define stats_ptr       b.ifr_ifru.ifru_data
 
@@ -146,6 +161,7 @@
 #define PPPIOCDISCONN	_IO('t', 57)		/* disconnect channel */
 #define PPPIOCATTCHAN	_IOW('t', 56, int)	/* attach to ppp channel */
 #define PPPIOCGCHAN	_IOR('t', 55, int)	/* get ppp channel number */
+#define PPPIOCGL2TPSTATS _IOR('t', 54, struct pppol2tp_ioc_stats)
 
 #define SIOCGPPPSTATS   (SIOCDEVPRIVATE + 0)
 #define SIOCGPPPVER     (SIOCDEVPRIVATE + 1)	/* NEVER change this!! */