Merge branch 'master' of git+ssh://galak@master.kernel.org/pub/scm/linux/kernel/git/galak/powerpc

1 files changed, 17 insertions, 22 deletions

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index a094ec49ccfa..307d01e15b2e 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);