From: Paul Mackerras <paulus@samba.org>
Somewhere along the line we lost the code that updates some fields of the
systemcfg structure that are used for translating timebase values to time
of day. I want to get rid of the systemcfg structure eventually, but
applications are using it (and in particular these fields) and I don't want
to break the ABI in a stable kernel series.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/ppc64/kernel/smp.c | 1 +
25-akpm/arch/ppc64/kernel/time.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff -puN arch/ppc64/kernel/smp.c~ppc64-set-time-related-systemcfg-fields arch/ppc64/kernel/smp.c
--- 25/arch/ppc64/kernel/smp.c~ppc64-set-time-related-systemcfg-fields 2004-08-15 13:44:50.247119904 -0700
+++ 25-akpm/arch/ppc64/kernel/smp.c 2004-08-15 13:44:50.252119144 -0700
@@ -843,6 +843,7 @@ void __init smp_prepare_cpus(unsigned in
* number of msecs off until someone does a settimeofday()
*/
do_gtod.tb_orig_stamp = tb_last_stamp;
+ systemcfg->tb_orig_stamp = tb_last_stamp;
look_for_more_cpus();
#endif
diff -puN arch/ppc64/kernel/time.c~ppc64-set-time-related-systemcfg-fields arch/ppc64/kernel/time.c
--- 25/arch/ppc64/kernel/time.c~ppc64-set-time-related-systemcfg-fields 2004-08-15 13:44:50.249119600 -0700
+++ 25-akpm/arch/ppc64/kernel/time.c 2004-08-15 13:44:50.254118840 -0700
@@ -101,6 +101,8 @@ extern unsigned long wall_jiffies;
extern unsigned long lpevent_count;
extern int smp_tb_synchronized;
+extern struct timezone sys_tz;
+
void ppc_adjtimex(void);
static unsigned adjusting_time = 0;
@@ -233,6 +235,8 @@ static void iSeries_tb_recal(void)
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
tb_to_xs = divres.result_low;
do_gtod.varp->tb_to_xs = tb_to_xs;
+ systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
+ systemcfg->tb_to_xs = tb_to_xs;
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
@@ -408,6 +412,7 @@ int do_settimeofday(struct timespec *tv)
new_xsec += new_sec * XSEC_PER_SEC;
if ( new_xsec > delta_xsec ) {
do_gtod.varp->stamp_xsec = new_xsec - delta_xsec;
+ systemcfg->stamp_xsec = new_xsec - delta_xsec;
}
else {
/* This is only for the case where the user is setting the time
@@ -416,8 +421,13 @@ int do_settimeofday(struct timespec *tv)
* the time to Jan 5, 1970 */
do_gtod.varp->stamp_xsec = new_xsec;
do_gtod.tb_orig_stamp = tb_last_stamp;
+ systemcfg->stamp_xsec = new_xsec;
+ systemcfg->tb_orig_stamp = tb_last_stamp;
}
+ systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
+ systemcfg->tz_dsttime = sys_tz.tz_dsttime;
+
write_sequnlock_irqrestore(&xtime_lock, flags);
clock_was_set();
return 0;
@@ -520,6 +530,11 @@ void __init time_init(void)
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
do_gtod.varp->tb_to_xs = tb_to_xs;
do_gtod.tb_to_us = tb_to_us;
+ systemcfg->tb_orig_stamp = tb_last_stamp;
+ systemcfg->tb_update_count = 0;
+ systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
+ systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
+ systemcfg->tb_to_xs = tb_to_xs;
xtime_sync_interval = tb_ticks_per_sec - (tb_ticks_per_sec/8);
next_xtime_sync_tb = tb_last_stamp + xtime_sync_interval;
@@ -655,6 +670,22 @@ void ppc_adjtimex(void)
do_gtod.varp = temp_varp;
do_gtod.var_idx = temp_idx;
+ /*
+ * tb_update_count is used to allow the problem state gettimeofday code
+ * to assure itself that it sees a consistent view of the tb_to_xs and
+ * stamp_xsec variables. It reads the tb_update_count, then reads
+ * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
+ * the two values of tb_update_count match and are even then the
+ * tb_to_xs and stamp_xsec values are consistent. If not, then it
+ * loops back and reads them again until this criteria is met.
+ */
+ ++(systemcfg->tb_update_count);
+ wmb();
+ systemcfg->tb_to_xs = new_tb_to_xs;
+ systemcfg->stamp_xsec = new_stamp_xsec;
+ wmb();
+ ++(systemcfg->tb_update_count);
+
write_sequnlock_irqrestore( &xtime_lock, flags );
}
_