1 files changed, 38 insertions, 30 deletions

diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
index 0e8977871b1f..0cd459baad68 100644
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -515,35 +515,14 @@ void unlock_ipi_call_lock(void)
 
 static struct call_data_struct *call_data;
 
-/**
- * smp_call_function(): Run a function on all other CPUs.
- * @func: The function to run. This must be fast and non-blocking.
- * @info: An arbitrary pointer to pass to the function.
- * @nonatomic: currently unused.
- * @wait: If true, wait (atomically) until function has completed on other CPUs.
- *
- * Returns 0 on success, else a negative status code. Does not return until
- * remote CPUs are nearly ready to execute <<func>> or are or have executed.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler.
- */
-int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
-			int wait)
+static void __smp_call_function(void (*func) (void *info), void *info,
+				int nonatomic, int wait)
 {
 	struct call_data_struct data;
-	int cpus;
-
-	/* Holding any lock stops cpus from going down. */
-	spin_lock(&call_lock);
-	cpus = num_online_cpus() - 1;
-	if (!cpus) {
-		spin_unlock(&call_lock);
-		return 0;
-	}
+	int cpus = num_online_cpus() - 1;
 
-	/* Can deadlock when called with interrupts disabled */
-	WARN_ON(irqs_disabled());
+	if (!cpus)
+		return;
 
 	data.func = func;
 	data.info = info;
@@ -565,6 +544,30 @@ int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 	if (wait)
 		while (atomic_read(&data.finished) != cpus)
 			cpu_relax();
+}
+
+/**
+ * smp_call_function(): Run a function on all other CPUs.
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @nonatomic: currently unused.
+ * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ *
+ * Returns 0 on success, else a negative status code. Does not return until
+ * remote CPUs are nearly ready to execute <<func>> or are or have executed.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.
+ */
+int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
+			int wait)
+{
+	/* Can deadlock when called with interrupts disabled */
+	WARN_ON(irqs_disabled());
+
+	/* Holding any lock stops cpus from going down. */
+	spin_lock(&call_lock);
+	__smp_call_function(func, info, nonatomic, wait);
 	spin_unlock(&call_lock);
 
 	return 0;
@@ -573,11 +576,11 @@ EXPORT_SYMBOL(smp_call_function);
 
 static void stop_this_cpu (void * dummy)
 {
+	local_irq_disable();
 	/*
 	 * Remove this CPU:
 	 */
 	cpu_clear(smp_processor_id(), cpu_online_map);
-	local_irq_disable();
 	disable_local_APIC();
 	if (cpu_data[smp_processor_id()].hlt_works_ok)
 		for(;;) halt();
@@ -590,11 +593,16 @@ static void stop_this_cpu (void * dummy)
 
 void smp_send_stop(void)
 {
-	smp_call_function(stop_this_cpu, NULL, 1, 0);
+	/* Don't deadlock on the call lock in panic */
+	int nolock = !spin_trylock(&call_lock);
+	unsigned long flags;
 
-	local_irq_disable();
+	local_irq_save(flags);
+	__smp_call_function(stop_this_cpu, NULL, 0, 0);
+	if (!nolock)
+		spin_unlock(&call_lock);
 	disable_local_APIC();
-	local_irq_enable();
+	local_irq_restore(flags);
 }
 
 /*