X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;ds=sidebyside;f=arch%2Fx86%2Flib%2Fdelay_64.c;h=4c441be92641a3ae295c8dea3db10b86323e7de2;hb=cb9aa97c21c59ad01c9514d7faf45dc166fba226;hp=2dbebd308347f21be2ad931ce480a6ade16e72b2;hpb=2843483d2eb02ad104edbe8b2429fb6a39d25063;p=linux-2.6-omap-h63xx.git

diff --git a/arch/x86/lib/delay_64.c b/arch/x86/lib/delay_64.c
index 2dbebd30834..4c441be9264 100644
--- a/arch/x86/lib/delay_64.c
+++ b/arch/x86/lib/delay_64.c
@@ -10,7 +10,11 @@
 
 #include <linux/module.h>
 #include <linux/sched.h>
+#include <linux/timex.h>
+#include <linux/preempt.h>
 #include <linux/delay.h>
+#include <linux/init.h>
+
 #include <asm/delay.h>
 #include <asm/msr.h>
 
@@ -18,7 +22,7 @@
 #include <asm/smp.h>
 #endif
 
-int read_current_timer(unsigned long *timer_value)
+int __devinit read_current_timer(unsigned long *timer_value)
 {
 	rdtscll(*timer_value);
 	return 0;
@@ -27,20 +31,44 @@ int read_current_timer(unsigned long *timer_value)
 void __delay(unsigned long loops)
 {
 	unsigned bclock, now;
-	
+	int cpu;
+
+	preempt_disable();
+	cpu = smp_processor_id();
 	rdtscl(bclock);
-	do
-	{
-		rep_nop(); 
+	for (;;) {
 		rdtscl(now);
+		if ((now - bclock) >= loops)
+			break;
+
+		/* Allow RT tasks to run */
+		preempt_enable();
+		rep_nop();
+		preempt_disable();
+
+		/*
+		 * It is possible that we moved to another CPU, and
+		 * since TSC's are per-cpu we need to calculate
+		 * that. The delay must guarantee that we wait "at
+		 * least" the amount of time. Being moved to another
+		 * CPU could make the wait longer but we just need to
+		 * make sure we waited long enough. Rebalance the
+		 * counter for this CPU.
+		 */
+		if (unlikely(cpu != smp_processor_id())) {
+			loops -= (now - bclock);
+			cpu = smp_processor_id();
+			rdtscl(bclock);
+		}
 	}
-	while((now-bclock) < loops);
+	preempt_enable();
 }
 EXPORT_SYMBOL(__delay);
 
 inline void __const_udelay(unsigned long xloops)
 {
-	__delay(((xloops * HZ * cpu_data[raw_smp_processor_id()].loops_per_jiffy) >> 32) + 1);
+	__delay(((xloops * HZ *
+		cpu_data(raw_smp_processor_id()).loops_per_jiffy) >> 32) + 1);
 }
 EXPORT_SYMBOL(__const_udelay);