[IPV6] ADDRCONF: Allow longer lifetime on 64bit archs.

- Allow longer lifetimes (>= 0x7fffffff/HZ) on 64bit archs
  by using unsigned long.
- Shadow this arithmetic overflow workaround by introducing
  helper functions: addrconf_timeout_fixup() and
  addrconf_finite_timeout().

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 0a2f0372df31..bbd3d583c6e6 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -94,6 +94,28 @@ extern void			addrconf_join_solict(struct net_device *dev,
 extern void			addrconf_leave_solict(struct inet6_dev *idev,
 					struct in6_addr *addr);
 
+static inline unsigned long addrconf_timeout_fixup(u32 timeout,
+						    unsigned unit)
+{
+	if (timeout == 0xffffffff)
+		return ~0UL;
+
+	/*
+	 * Avoid arithmetic overflow.
+	 * Assuming unit is constant and non-zero, this "if" statement
+	 * will go away on 64bit archs.
+	 */
+	if (0xfffffffe > LONG_MAX / unit && timeout > LONG_MAX / unit)
+		return LONG_MAX / unit;
+
+	return timeout;
+}
+
+static inline int addrconf_finite_timeout(unsigned long timeout)
+{
+	return ~timeout;
+}
+
 /*
  *	IPv6 Address Label subsystem (addrlabel.c)
  */