x86: add C1E aware idle function, fix

On Tue, 17 Jun 2008, Rafael J. Wysocki wrote:
>
> BTW, with the C1E patches reverted I don't get the
> WARNING: at /home/rafael/src/linux-next/kernel/smp.c:215 smp_call_function_single+0x3d/0xa2
> in the log.  Thomas?

The BROADCAST_FORCE notification uses smp_function_call and therefor
must be run with interrupts enabled.

While at it, add a comment for the BROADCAST_EXIT notifier as well.

Reported-and-bisected-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 68ad3539b143a57051d2b8b8f5939a474dac9917..4061d63aabe74bb12f32f5d162c564240ae8d8a5 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -267,17 +267,29 @@ static void c1e_idle(void)
 
                if (!cpu_isset(cpu, c1e_mask)) {
                        cpu_set(cpu, c1e_mask);
-                       /* Force broadcast so ACPI can not interfere */
+                       /*
+                        * Force broadcast so ACPI can not interfere. Needs
+                        * to run with interrupts enabled as it uses
+                        * smp_function_call.
+                        */
+                       local_irq_enable();
                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
                                           &cpu);
                        printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
                               cpu);
+                       local_irq_disable();
                }
                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
+
                default_idle();
-               local_irq_disable();
-               clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
-               local_irq_enable();
+
+               /*
+                * The switch back from broadcast mode needs to be
+                * called with interrupts disabled.
+                */
+                local_irq_disable();
+                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
+                local_irq_enable();
        } else
                default_idle();
 }