1 files changed, 29 insertions, 8 deletions

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index cefeee81c52e..be35ffae10f0 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -76,6 +76,8 @@ void smp_call_function_interrupt(void);
 
 int smt_enabled_at_boot = 1;
 
+static int ipi_fail_ok;
+
 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
 
 #ifdef CONFIG_PPC64
@@ -204,8 +206,6 @@ static int __smp_call_function_map(void (*func) (void *info), void *info,
         if (wait)
                 atomic_set(&data.finished, 0);
 
-        spin_lock(&call_lock);
-
         /* remove 'self' from the map */
         if (cpu_isset(smp_processor_id(), map))
                 cpu_clear(smp_processor_id(), map);
@@ -232,7 +232,8 @@ static int __smp_call_function_map(void (*func) (void *info), void *info,
                         printk("smp_call_function on cpu %d: other cpus not "
                                 "responding (%d)\n", smp_processor_id(),
                                 atomic_read(&data.started));
-                        debugger(NULL);
+                        if (!ipi_fail_ok)
+                                debugger(NULL);
                         goto out;
                 }
         }
@@ -259,15 +260,18 @@ static int __smp_call_function_map(void (*func) (void *info), void *info,
  out:
         call_data = NULL;
         HMT_medium();
-        spin_unlock(&call_lock);
         return ret;
 }
 
 static int __smp_call_function(void (*func)(void *info), void *info,
                                int nonatomic, int wait)
 {
-        return __smp_call_function_map(func, info, nonatomic, wait,
+        int ret;
+        spin_lock(&call_lock);
+        ret =__smp_call_function_map(func, info, nonatomic, wait,
                                        cpu_online_map);
+        spin_unlock(&call_lock);
+        return ret;
 }
 
 int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
@@ -293,9 +297,11 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
                 return -EINVAL;
 
         cpu_set(cpu, map);
-        if (cpu != get_cpu())
+        if (cpu != get_cpu()) {
+                spin_lock(&call_lock);
                 ret = __smp_call_function_map(func, info, nonatomic, wait, map);
-        else {
+                spin_unlock(&call_lock);
+        } else {
                 local_irq_disable();
                 func(info);
                 local_irq_enable();
@@ -307,7 +313,22 @@ EXPORT_SYMBOL(smp_call_function_single);
 
 void smp_send_stop(void)
 {
-        __smp_call_function(stop_this_cpu, NULL, 1, 0);
+        int nolock;
+
+        /* It's OK to fail sending the IPI, since the alternative is to
+         * be stuck forever waiting on the other CPU to take the interrupt.
+         *
+         * It's better to at least continue and go through reboot, since this
+         * function is usually called at panic or reboot time in the first
+         * place.
+         */
+        ipi_fail_ok = 1;
+
+        /* Don't deadlock in case we got called through panic */
+        nolock = !spin_trylock(&call_lock);
+        __smp_call_function_map(stop_this_cpu, NULL, 1, 0, cpu_online_map);
+        if (!nolock)
+                spin_unlock(&call_lock);
 }
 
 void smp_call_function_interrupt(void)