[S390] nohz/sclp: disable timer on synchronous waits.

sclp_sync_wait wait synchronously for an sclp interrupt and disables
timer interrupts. However on the irq enter paths there is an extra
check if a timer interrupt would be due and calls the timer callback.
This would schedule softirqs in the wrong context.
So introduce local_tick_enable/disable which prevents this.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
index 3c8b25e6c345..1fd8f2193ed8 100644
--- a/drivers/s390/char/sclp.c
+++ b/drivers/s390/char/sclp.c
@@ -399,6 +399,7 @@ sclp_tod_from_jiffies(unsigned long jiffies)
 void
 sclp_sync_wait(void)
 {
+        unsigned long long old_tick;
         unsigned long flags;
         unsigned long cr0, cr0_sync;
         u64 timeout;
@@ -419,11 +420,12 @@ sclp_sync_wait(void)
         if (!irq_context)
                 local_bh_disable();
         /* Enable service-signal interruption, disable timer interrupts */
+        old_tick = local_tick_disable();
         trace_hardirqs_on();
         __ctl_store(cr0, 0, 0);
         cr0_sync = cr0;
+        cr0_sync &= 0xffff00a0;
         cr0_sync |= 0x00000200;
-        cr0_sync &= 0xFFFFF3AC;
         __ctl_load(cr0_sync, 0, 0);
         __raw_local_irq_stosm(0x01);
         /* Loop until driver state indicates finished request */
@@ -439,9 +441,9 @@ sclp_sync_wait(void)
         __ctl_load(cr0, 0, 0);
         if (!irq_context)
                 _local_bh_enable();
+        local_tick_enable(old_tick);
         local_irq_restore(flags);
 }
-
 EXPORT_SYMBOL(sclp_sync_wait);
 
 /* Dispatch changes in send and receive mask to registered listeners. */