compat: Backport prandom_u32_max().

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>

Author: joestringer

acinclude.m4

@@ -381,6 +381,7 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
                   [OVS_DEFINE([HAVE_NF_CT_TMPL_ALLOC_TAKES_STRUCT_ZONE])])
 
   OVS_GREP_IFELSE([$KSRC/include/linux/random.h], [prandom_u32])
+  OVS_GREP_IFELSE([$KSRC/include/linux/random.h], [prandom_u32_max])
 
   OVS_GREP_IFELSE([$KSRC/include/net/rtnetlink.h], [get_link_net])
   OVS_GREP_IFELSE([$KSRC/include/net/rtnetlink.h], [name_assign_type])

datapath/linux/compat/include/linux/random.h

@@ -7,4 +7,11 @@
 #define prandom_u32()		random32()
 #endif
 
+#ifndef HAVE_PRANDOM_U32_MAX
+static inline u32 prandom_u32_max(u32 ep_ro)
+{
+	return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
+}
+#endif
+
 #endif