From: Karel Zak <kzak@redhat.com>
Date: Tue, 12 Aug 2008 11:58:51 +0000 (+0200)
Subject: hwclock: use time limit for synchronization busy wait
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=982a4a5d98c7034004ec04bff7faea6e1dfcf131;p=util-linux

hwclock: use time limit for synchronization busy wait

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/hwclock/clock.h b/hwclock/clock.h
index 6e8a9b4c..cbdf9991 100644
--- a/hwclock/clock.h
+++ b/hwclock/clock.h
@@ -33,6 +33,7 @@ extern void outsyserr(char *msg, ...)
 #else
         ;
 #endif
+extern double time_diff(struct timeval subtrahend, struct timeval subtractor);
 /* cmos.c */
 extern void set_cmos_epoch(int ARCconsole, int SRM);
 extern void set_cmos_access(int Jensen, int funky_toy);
diff --git a/hwclock/hwclock.c b/hwclock/hwclock.c
index 82da273d..c08ae3f5 100644
--- a/hwclock/hwclock.c
+++ b/hwclock/hwclock.c
@@ -182,7 +182,7 @@ read_date_from_file (struct tm *tm) {
   write_date_to_file (tm);
 }
 
-static double
+double
 time_diff(struct timeval subtrahend, struct timeval subtractor) {
 /*---------------------------------------------------------------------------
   The difference in seconds between two times in "timeval" format.
diff --git a/hwclock/rtc.c b/hwclock/rtc.c
index 3eb1f4eb..e59414fd 100644
--- a/hwclock/rtc.c
+++ b/hwclock/rtc.c
@@ -179,8 +179,8 @@ busywait_for_rtc_clock_tick(const int rtc_fd) {
   struct tm start_time;
     /* The time when we were called (and started waiting) */
   struct tm nowtime;
-  int i;  /* local loop index */
   int rc;
+  struct timeval begin, now;
 
   if (debug)
     printf(_("Waiting in loop for time from %s to change\n"),
@@ -191,25 +191,26 @@ busywait_for_rtc_clock_tick(const int rtc_fd) {
     return 1;
 
   /* Wait for change.  Should be within a second, but in case something
-     weird happens, we have a limit on this loop to reduce the impact
-     of this failure.
-     */
-  for (i = 0;
-       (rc = do_rtc_read_ioctl(rtc_fd, &nowtime)) == 0
-        && start_time.tm_sec == nowtime.tm_sec;
-       i++)
-    if (i >= 1000000) {
+   * weird happens, we have a time limit (1.5s) on this loop to reduce the
+   * impact of this failure.
+   */
+  gettimeofday(&begin, NULL);
+  do {
+    rc = do_rtc_read_ioctl(rtc_fd, &nowtime);
+    if (rc || start_time.tm_sec != nowtime.tm_sec)
+      break;
+    gettimeofday(&now, NULL);
+    if (time_diff(now, begin) > 1.5) {
       fprintf(stderr, _("Timed out waiting for time change.\n"));
       return 2;
     }
+  } while(1);
 
   if (rc)
     return 3;
   return 0;
 }
 
-
-
 static int
 synchronize_to_clock_tick_rtc(void) {
 /*----------------------------------------------------------------------------