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-rw-r--r--arch/ia64/kernel/time.c39
1 files changed, 17 insertions, 22 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index a094ec49ccf..307d01e15b2 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -250,32 +250,27 @@ time_init (void)
set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
}
-#define SMALLUSECS 100
-
-void
-udelay (unsigned long usecs)
+/*
+ * Generic udelay assumes that if preemption is allowed and the thread
+ * migrates to another CPU, that the ITC values are synchronized across
+ * all CPUs.
+ */
+static void
+ia64_itc_udelay (unsigned long usecs)
{
- unsigned long start;
- unsigned long cycles;
- unsigned long smallusecs;
+ unsigned long start = ia64_get_itc();
+ unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
- /*
- * Execute the non-preemptible delay loop (because the ITC might
- * not be synchronized between CPUS) in relatively short time
- * chunks, allowing preemption between the chunks.
- */
- while (usecs > 0) {
- smallusecs = (usecs > SMALLUSECS) ? SMALLUSECS : usecs;
- preempt_disable();
- cycles = smallusecs*local_cpu_data->cyc_per_usec;
- start = ia64_get_itc();
+ while (time_before(ia64_get_itc(), end))
+ cpu_relax();
+}
- while (ia64_get_itc() - start < cycles)
- cpu_relax();
+void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
- preempt_enable();
- usecs -= smallusecs;
- }
+void
+udelay (unsigned long usecs)
+{
+ (*ia64_udelay)(usecs);
}
EXPORT_SYMBOL(udelay);