genirq: Support per-IRQ thread disabling.

This adds support for disabling threading on a per-IRQ basis via the IRQ
status instead of the IRQ flow, which is necessary for interrupts that
don't follow the natural IRQ flow channels, such as those that are
virtually created.

The new APIs added are simply:

	irq_set_thread()
	irq_set_nothread()

which follow the rest of the IRQ status routines.

Chained handlers also have IRQ_NOTHREAD set on them automatically, making
the lack of threading explicit rather than implicit. Subsequently, the
nothread flag can be viewed through the standard genirq debugging
facilities.

[ tglx: Fixed cleanup fallout ]

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Link: http://lkml.kernel.org/r/%3C20110406210135.GF18426%40linux-sh.org%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

4 files changed, 21 insertions, 1 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 4af1e2b244cb..52d856d513ff 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -573,6 +573,7 @@ __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
         if (handle != handle_bad_irq && is_chained) {
                 irq_settings_set_noprobe(desc);
                 irq_settings_set_norequest(desc);
+                irq_settings_set_nothread(desc);
                 irq_startup(desc);
         }
 out:
diff --git a/kernel/irq/debug.h b/kernel/irq/debug.h
index 306cba37e9a5..97a8bfadc88a 100644
--- a/kernel/irq/debug.h
+++ b/kernel/irq/debug.h
@@ -27,6 +27,7 @@ static inline void print_irq_desc(unsigned int irq, struct irq_desc *desc)
         P(IRQ_PER_CPU);
         P(IRQ_NOPROBE);
         P(IRQ_NOREQUEST);
+        P(IRQ_NOTHREAD);
         P(IRQ_NOAUTOEN);
 
         PS(IRQS_AUTODETECT);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 07c1611f3899..f7ce0021e1c4 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -900,7 +900,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                  */
                 new->handler = irq_nested_primary_handler;
         } else {
-                irq_setup_forced_threading(new);
+                if (irq_settings_can_thread(desc))
+                        irq_setup_forced_threading(new);
         }
 
         /*
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index 0d91730b6330..f1667833d444 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -8,6 +8,7 @@ enum {
         _IRQ_LEVEL              = IRQ_LEVEL,
         _IRQ_NOPROBE            = IRQ_NOPROBE,
         _IRQ_NOREQUEST          = IRQ_NOREQUEST,
+        _IRQ_NOTHREAD           = IRQ_NOTHREAD,
         _IRQ_NOAUTOEN           = IRQ_NOAUTOEN,
         _IRQ_MOVE_PCNTXT        = IRQ_MOVE_PCNTXT,
         _IRQ_NO_BALANCING       = IRQ_NO_BALANCING,
@@ -20,6 +21,7 @@ enum {
 #define IRQ_LEVEL               GOT_YOU_MORON
 #define IRQ_NOPROBE             GOT_YOU_MORON
 #define IRQ_NOREQUEST           GOT_YOU_MORON
+#define IRQ_NOTHREAD            GOT_YOU_MORON
 #define IRQ_NOAUTOEN            GOT_YOU_MORON
 #define IRQ_NESTED_THREAD       GOT_YOU_MORON
 #undef IRQF_MODIFY_MASK
@@ -94,6 +96,21 @@ static inline void irq_settings_set_norequest(struct irq_desc *desc)
         desc->status_use_accessors |= _IRQ_NOREQUEST;
 }
 
+static inline bool irq_settings_can_thread(struct irq_desc *desc)
+{
+        return !(desc->status_use_accessors & _IRQ_NOTHREAD);
+}
+
+static inline void irq_settings_clr_nothread(struct irq_desc *desc)
+{
+        desc->status_use_accessors &= ~_IRQ_NOTHREAD;
+}
+
+static inline void irq_settings_set_nothread(struct irq_desc *desc)
+{
+        desc->status_use_accessors |= _IRQ_NOTHREAD;
+}
+
 static inline bool irq_settings_can_probe(struct irq_desc *desc)
 {
         return !(desc->status_use_accessors & _IRQ_NOPROBE);