IPVS: Add debug macros for v4 and v6 address output

Add some debugging macros that allow conditional output of either v4 or v6
addresses, depending on an 'af' parameter. This is done by creating a
temporary string buffer in an outer debug macro and writing addresses'
string representations into it from another macro which can only be used
when inside the outer one.
Signed-off-by: Julius Volz <juliusv@google.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

include/net/ip_vs.h

@@ -78,6 +78,46 @@ static inline int ip_vs_addr_equal(int af, const union nf_inet_addr *a,
 #include <linux/net.h>
 
 extern int ip_vs_get_debug_level(void);
+
+static inline const char *ip_vs_dbg_addr(int af, char *buf, size_t buf_len,
+					 const union nf_inet_addr *addr,
+					 int *idx)
+{
+	int len;
+#ifdef CONFIG_IP_VS_IPV6
+	if (af == AF_INET6)
+		len = snprintf(&buf[*idx], buf_len - *idx, "[" NIP6_FMT "]",
+			       NIP6(addr->in6)) + 1;
+	else
+#endif
+		len = snprintf(&buf[*idx], buf_len - *idx, NIPQUAD_FMT,
+			       NIPQUAD(addr->ip)) + 1;
+
+	*idx += len;
+	BUG_ON(*idx > buf_len + 1);
+	return &buf[*idx - len];
+}
+
+#define IP_VS_DBG_BUF(level, msg...)			\
+    do {						\
+	    char ip_vs_dbg_buf[160];			\
+	    int ip_vs_dbg_idx = 0;			\
+	    if (level <= ip_vs_get_debug_level())	\
+		    printk(KERN_DEBUG "IPVS: " msg);	\
+    } while (0)
+#define IP_VS_ERR_BUF(msg...)				\
+    do {						\
+	    char ip_vs_dbg_buf[160];			\
+	    int ip_vs_dbg_idx = 0;			\
+	    printk(KERN_ERR "IPVS: " msg);		\
+    } while (0)
+
+/* Only use from within IP_VS_DBG_BUF() or IP_VS_ERR_BUF macros */
+#define IP_VS_DBG_ADDR(af, addr)			\
+    ip_vs_dbg_addr(af, ip_vs_dbg_buf,			\
+		   sizeof(ip_vs_dbg_buf), addr,		\
+		   &ip_vs_dbg_idx)
+
 #define IP_VS_DBG(level, msg...)			\
     do {						\
 	    if (level <= ip_vs_get_debug_level())	\
@@ -100,6 +140,8 @@ extern int ip_vs_get_debug_level(void);
 		pp->debug_packet(pp, skb, ofs, msg);	\
     } while (0)
 #else	/* NO DEBUGGING at ALL */
+#define IP_VS_DBG_BUF(level, msg...)  do {} while (0)
+#define IP_VS_ERR_BUF(msg...)  do {} while (0)
 #define IP_VS_DBG(level, msg...)  do {} while (0)
 #define IP_VS_DBG_RL(msg...)  do {} while (0)
 #define IP_VS_DBG_PKT(level, pp, skb, ofs, msg)		do {} while (0)