[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, 2 insertions, 2 deletions

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index eae21a8ac72d..fc6ab6094df8 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -43,7 +43,7 @@ void __udelay(unsigned long usecs)
                 local_bh_disable();
         local_irq_save(flags);
         if (raw_irqs_disabled_flags(flags)) {
-                old_cc = S390_lowcore.clock_comparator;
+                old_cc = local_tick_disable();
                 S390_lowcore.clock_comparator = -1ULL;
                 __ctl_store(cr0, 0, 0);
                 dummy = (cr0 & 0xffff00e0) | 0x00000800;
@@ -65,7 +65,7 @@ void __udelay(unsigned long usecs)
 
         if (raw_irqs_disabled_flags(flags)) {
                 __ctl_load(cr0, 0, 0);
-                S390_lowcore.clock_comparator = old_cc;
+                local_tick_enable(old_cc);
         }
         if (!irq_context)
                 _local_bh_enable();