genirq: Add IRQF_RESUME_EARLY and resume such IRQs earlier

This adds a mechanism to resume selected IRQs during syscore_resume
instead of dpm_resume_noirq.

Under Xen we need to resume IRQs associated with IPIs early enough
that the resched IPI is unmasked and we can therefore schedule
ourselves out of the stop_machine where the suspend/resume takes
place.

This issue was introduced by 676dc3cf5bc3 "xen: Use IRQF_FORCE_RESUME".

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1318713254.11016.52.camel@dagon.hellion.org.uk
Cc: stable@kernel.org (at least to 2.6.32.y)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 41 insertions, 7 deletions

diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index f76fc00c9877..15e53b1766a6 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -9,6 +9,7 @@
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
+#include <linux/syscore_ops.h>
 
 #include "internals.h"
 
@@ -39,25 +40,58 @@ void suspend_device_irqs(void)
 }
 EXPORT_SYMBOL_GPL(suspend_device_irqs);
 
-/**
- * resume_device_irqs - enable interrupt lines disabled by suspend_device_irqs()
- *
- * Enable all interrupt lines previously disabled by suspend_device_irqs() that
- * have the IRQS_SUSPENDED flag set.
- */
-void resume_device_irqs(void)
+static void resume_irqs(bool want_early)
 {
         struct irq_desc *desc;
         int irq;
 
         for_each_irq_desc(irq, desc) {
                 unsigned long flags;
+                bool is_early = desc->action &&
+                        desc->action->flags & IRQF_EARLY_RESUME;
+
+                if (is_early != want_early)
+                        continue;
 
                 raw_spin_lock_irqsave(&desc->lock, flags);
                 __enable_irq(desc, irq, true);
                 raw_spin_unlock_irqrestore(&desc->lock, flags);
         }
 }
+
+/**
+ * irq_pm_syscore_ops - enable interrupt lines early
+ *
+ * Enable all interrupt lines with %IRQF_EARLY_RESUME set.
+ */
+static void irq_pm_syscore_resume(void)
+{
+        resume_irqs(true);
+}
+
+static struct syscore_ops irq_pm_syscore_ops = {
+        .resume         = irq_pm_syscore_resume,
+};
+
+static int __init irq_pm_init_ops(void)
+{
+        register_syscore_ops(&irq_pm_syscore_ops);
+        return 0;
+}
+
+device_initcall(irq_pm_init_ops);
+
+/**
+ * resume_device_irqs - enable interrupt lines disabled by suspend_device_irqs()
+ *
+ * Enable all non-%IRQF_EARLY_RESUME interrupt lines previously
+ * disabled by suspend_device_irqs() that have the IRQS_SUSPENDED flag
+ * set as well as those with %IRQF_FORCE_RESUME.
+ */
+void resume_device_irqs(void)
+{
+        resume_irqs(false);
+}
 EXPORT_SYMBOL_GPL(resume_device_irqs);
 
 /**