svn commit: r216015 - stable/8/sys/kern

[Colin Percival]

Author: cperciva
Date: Sun Nov 28 18:59:52 2010
New Revision: 216015
URL: http://svn.freebsd.org/changeset/base/216015

Log:
  MFC r215665,r215732: Don't lose seconds to integer overflow if we go more
  than one second between calls to tc_windup.

Modified:
  stable/8/sys/kern/kern_tc.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)

Modified: stable/8/sys/kern/kern_tc.c
==============================================================================
--- stable/8/sys/kern/kern_tc.c	Sun Nov 28 18:53:57 2010	(r216014)
+++ stable/8/sys/kern/kern_tc.c	Sun Nov 28 18:59:52 2010	(r216015)
@@ -440,6 +440,16 @@ tc_windup(void)
 		ncount = 0;
 	th->th_offset_count += delta;
 	th->th_offset_count &= th->th_counter->tc_counter_mask;
+	while (delta > th->th_counter->tc_frequency) {
+		/* Eat complete unadjusted seconds. */
+		delta -= th->th_counter->tc_frequency;
+		th->th_offset.sec++;
+	}
+	if ((delta > th->th_counter->tc_frequency / 2) &&
+	    (th->th_scale * delta < ((uint64_t)1 << 63))) {
+		/* The product th_scale * delta just barely overflows. */
+		th->th_offset.sec++;
+	}
 	bintime_addx(&th->th_offset, th->th_scale * delta);
 
 	/*