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>

1 files changed, 16 insertions, 4 deletions

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 68ad3539b14..4061d63aabe 100644
--- 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();
 }