1 files changed, 45 insertions, 17 deletions

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index aa2caa67299a..9fbf8430c849 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -38,15 +38,40 @@ static void r3081_wait(void)
 
 static void r39xx_wait(void)
 {
-	unsigned long cfg = read_c0_conf();
-	write_c0_conf(cfg | TX39_CONF_HALT);
+	local_irq_disable();
+	if (!need_resched())
+		write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
+	local_irq_enable();
 }
 
+/*
+ * There is a race when WAIT instruction executed with interrupt
+ * enabled.
+ * But it is implementation-dependent wheter the pipelie restarts when
+ * a non-enabled interrupt is requested.
+ */
 static void r4k_wait(void)
 {
-	__asm__(".set\tmips3\n\t"
-		"wait\n\t"
-		".set\tmips0");
+	__asm__("	.set	mips3			\n"
+		"	wait				\n"
+		"	.set	mips0			\n");
+}
+
+/*
+ * This variant is preferable as it allows testing need_resched and going to
+ * sleep depending on the outcome atomically.  Unfortunately the "It is
+ * implementation-dependent whether the pipeline restarts when a non-enabled
+ * interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes
+ * using this version a gamble.
+ */
+static void r4k_wait_irqoff(void)
+{
+	local_irq_disable();
+	if (!need_resched())
+		__asm__("	.set	mips3		\n"
+			"	wait			\n"
+			"	.set	mips0		\n");
+	local_irq_enable();
 }
 
 /* The Au1xxx wait is available only if using 32khz counter or
@@ -56,17 +81,17 @@ int allow_au1k_wait;
 static void au1k_wait(void)
 {
 	/* using the wait instruction makes CP0 counter unusable */
-	__asm__(".set mips3\n\t"
-		"cache 0x14, 0(%0)\n\t"
-		"cache 0x14, 32(%0)\n\t"
-		"sync\n\t"
-		"nop\n\t"
-		"wait\n\t"
-		"nop\n\t"
-		"nop\n\t"
-		"nop\n\t"
-		"nop\n\t"
-		".set mips0\n\t"
+	__asm__("	.set	mips3			\n"
+		"	cache	0x14, 0(%0)		\n"
+		"	cache	0x14, 32(%0)		\n"
+		"	sync				\n"
+		"	nop				\n"
+		"	wait				\n"
+		"	nop				\n"
+		"	nop				\n"
+		"	nop				\n"
+		"	nop				\n"
+		"	.set	mips0			\n"
 		: : "r" (au1k_wait));
 }
 
@@ -111,7 +136,6 @@ static inline void check_wait(void)
 	case CPU_NEVADA:
 	case CPU_RM7000:
 	case CPU_RM9000:
-	case CPU_TX49XX:
 	case CPU_4KC:
 	case CPU_4KEC:
 	case CPU_4KSC:
@@ -125,6 +149,10 @@ static inline void check_wait(void)
 		cpu_wait = r4k_wait;
 		printk(" available.\n");
 		break;
+	case CPU_TX49XX:
+		cpu_wait = r4k_wait_irqoff;
+		printk(" available.\n");
+		break;
 	case CPU_AU1000:
 	case CPU_AU1100:
 	case CPU_AU1500: