[S390] stp synchronization retry timer

Add a timer that retries the clock synchronization via the server time
protocol if there is a usable clock but the synchronization failed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index f72d41068dc2..05f93e77870b 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -1423,6 +1423,7 @@ static void *stp_page;
 static void stp_work_fn(struct work_struct *work);
 static DEFINE_MUTEX(stp_work_mutex);
 static DECLARE_WORK(stp_work, stp_work_fn);
+static struct timer_list stp_timer;
 
 static int __init early_parse_stp(char *p)
 {
@@ -1454,10 +1455,16 @@ static void __init stp_reset(void)
         }
 }
 
+static void stp_timeout(unsigned long dummy)
+{
+        queue_work(time_sync_wq, &stp_work);
+}
+
 static int __init stp_init(void)
 {
         if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
                 return 0;
+        setup_timer(&stp_timer, stp_timeout, 0UL);
         time_init_wq();
         if (!stp_online)
                 return 0;
@@ -1565,6 +1572,7 @@ static void stp_work_fn(struct work_struct *work)
 
         if (!stp_online) {
                 chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
+                del_timer_sync(&stp_timer);
                 goto out_unlock;
         }
 
@@ -1586,6 +1594,13 @@ static void stp_work_fn(struct work_struct *work)
         stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map);
         put_online_cpus();
 
+        if (!check_sync_clock())
+                /*
+                 * There is a usable clock but the synchonization failed.
+                 * Retry after a second.
+                 */
+                mod_timer(&stp_timer, jiffies + HZ);
+
 out_unlock:
         mutex_unlock(&stp_work_mutex);
 }