2 files changed, 56 insertions, 34 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index ca114fe46ffb..06acb1a18bbc 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -169,6 +169,8 @@ void init_cpu_timer(void)
 
 static void clock_comparator_interrupt(__u16 code)
 {
+        if (S390_lowcore.clock_comparator == -1ULL)
+                set_clock_comparator(S390_lowcore.clock_comparator);
 }
 
 static void etr_timing_alert(struct etr_irq_parm *);
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index fc6ab6094df8..0953cee05efc 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -1,14 +1,9 @@
 /*
- *  arch/s390/lib/delay.c
  *    Precise Delay Loops for S390
  *
- *  S390 version
- *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
- *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
- *
- *  Derived from "arch/i386/lib/delay.c"
- *    Copyright (C) 1993 Linus Torvalds
- *    Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
+ *    Copyright IBM Corp. 1999,2008
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
+ *               Heiko Carstens <heiko.carstens@de.ibm.com>,
  */
 
 #include <linux/sched.h>
@@ -29,30 +24,31 @@ void __delay(unsigned long loops)
         asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
 }
 
-/*
- * Waits for 'usecs' microseconds using the TOD clock comparator.
- */
-void __udelay(unsigned long usecs)
+static void __udelay_disabled(unsigned long usecs)
 {
-        u64 end, time, old_cc = 0;
-        unsigned long flags, cr0, mask, dummy;
-        int irq_context;
+        unsigned long mask, cr0, cr0_saved;
+        u64 clock_saved;
 
-        irq_context = in_interrupt();
-        if (!irq_context)
-                local_bh_disable();
-        local_irq_save(flags);
-        if (raw_irqs_disabled_flags(flags)) {
-                old_cc = local_tick_disable();
-                S390_lowcore.clock_comparator = -1ULL;
-                __ctl_store(cr0, 0, 0);
-                dummy = (cr0 & 0xffff00e0) | 0x00000800;
-                __ctl_load(dummy , 0, 0);
-                mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
-        } else
-                mask = psw_kernel_bits | PSW_MASK_WAIT |
-                        PSW_MASK_EXT | PSW_MASK_IO;
+        clock_saved = local_tick_disable();
+        set_clock_comparator(get_clock() + ((u64) usecs << 12));
+        __ctl_store(cr0_saved, 0, 0);
+        cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
+        __ctl_load(cr0 , 0, 0);
+        mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
+        trace_hardirqs_on();
+        __load_psw_mask(mask);
+        local_irq_disable();
+        __ctl_load(cr0_saved, 0, 0);
+        local_tick_enable(clock_saved);
+        set_clock_comparator(S390_lowcore.clock_comparator);
+}
 
+static void __udelay_enabled(unsigned long usecs)
+{
+        unsigned long mask;
+        u64 end, time;
+
+        mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
         end = get_clock() + ((u64) usecs << 12);
         do {
                 time = end < S390_lowcore.clock_comparator ?
@@ -62,13 +58,37 @@ void __udelay(unsigned long usecs)
                 __load_psw_mask(mask);
                 local_irq_disable();
         } while (get_clock() < end);
+        set_clock_comparator(S390_lowcore.clock_comparator);
+}
 
-        if (raw_irqs_disabled_flags(flags)) {
-                __ctl_load(cr0, 0, 0);
-                local_tick_enable(old_cc);
+/*
+ * Waits for 'usecs' microseconds using the TOD clock comparator.
+ */
+void __udelay(unsigned long usecs)
+{
+        unsigned long flags;
+
+        preempt_disable();
+        local_irq_save(flags);
+        if (in_irq()) {
+                __udelay_disabled(usecs);
+                goto out;
+        }
+        if (in_softirq()) {
+                if (raw_irqs_disabled_flags(flags))
+                        __udelay_disabled(usecs);
+                else
+                        __udelay_enabled(usecs);
+                goto out;
         }
-        if (!irq_context)
+        if (raw_irqs_disabled_flags(flags)) {
+                local_bh_disable();
+                __udelay_disabled(usecs);
                 _local_bh_enable();
-        set_clock_comparator(S390_lowcore.clock_comparator);
+                goto out;
+        }
+        __udelay_enabled(usecs);
+out:
         local_irq_restore(flags);
+        preempt_enable();
 }