X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=arch%2Fx86%2Flib%2Fdelay_64.c;h=4c441be92641a3ae295c8dea3db10b86323e7de2;hp=bbc610518516b11c4bdbe1d10dacd29ce41130c6;hb=065cb3dfe24978651caedfa54da585388ad15dde;hpb=37969581301e50872a1ae84dc73962b5f7ee6b76

diff --git a/arch/x86/lib/delay_64.c b/arch/x86/lib/delay_64.c
index bbc610518516..4c441be92641 100644
--- a/arch/x86/lib/delay_64.c
+++ b/arch/x86/lib/delay_64.c
@@ -31,14 +31,36 @@ int __devinit read_current_timer(unsigned long *timer_value)
 void __delay(unsigned long loops)
 {
 	unsigned bclock, now;
+	int cpu;
 
-	preempt_disable();		/* TSC's are pre-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);