[PATCH] Add irq flag to disable balancing for an interrupt

Add a flag so we can prevent the irq balancing of an interrupt.  Move the
bits, so we have room for more :)

Necessary for the ability to setup clocksources more flexible (e.g.  use the
different HPET channels per CPU)

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 35 insertions, 20 deletions

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index e30ccedad0b9..c76be1110922 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -482,8 +482,8 @@ static void do_irq_balance(void)
                 package_index = CPU_TO_PACKAGEINDEX(i);
                 for (j = 0; j < NR_IRQS; j++) {
                         unsigned long value_now, delta;
-                        /* Is this an active IRQ? */
-                        if (!irq_desc[j].action)
+                        /* Is this an active IRQ or balancing disabled ? */
+                        if (!irq_desc[j].action || irq_balancing_disabled(j))
                                 continue;
                         if ( package_index == i )
                                 IRQ_DELTA(package_index,j) = 0;
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 5a8ba0b8ccba..690113d07698 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -42,6 +42,8 @@
  * IRQF_SHARED - allow sharing the irq among several devices
  * IRQF_PROBE_SHARED - set by callers when they expect sharing mismatches to occur
  * IRQF_TIMER - Flag to mark this interrupt as timer interrupt
+ * IRQF_PERCPU - Interrupt is per cpu
+ * IRQF_NOBALANCING - Flag to exclude this interrupt from irq balancing
  */
 #define IRQF_DISABLED           0x00000020
 #define IRQF_SAMPLE_RANDOM      0x00000040
@@ -49,6 +51,7 @@
 #define IRQF_PROBE_SHARED       0x00000100
 #define IRQF_TIMER              0x00000200
 #define IRQF_PERCPU             0x00000400
+#define IRQF_NOBALANCING        0x00000800
 
 /*
  * Migration helpers. Scheduled for removal in 1/2007
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 5504b671357f..8930fb0ac9c7 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -31,7 +31,7 @@ typedef	void fastcall (*irq_flow_handler_t)(unsigned int irq,
 /*
  * IRQ line status.
  *
- * Bits 0-16 are reserved for the IRQF_* bits in linux/interrupt.h
+ * Bits 0-7 are reserved for the IRQF_* bits in linux/interrupt.h
  *
  * IRQ types
  */
@@ -45,28 +45,31 @@ typedef	void fastcall (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_TYPE_PROBE          0x00000010      /* Probing in progress */
 
 /* Internal flags */
-#define IRQ_INPROGRESS          0x00010000      /* IRQ handler active - do not enter! */
-#define IRQ_DISABLED            0x00020000      /* IRQ disabled - do not enter! */
-#define IRQ_PENDING             0x00040000      /* IRQ pending - replay on enable */
-#define IRQ_REPLAY              0x00080000      /* IRQ has been replayed but not acked yet */
-#define IRQ_AUTODETECT          0x00100000      /* IRQ is being autodetected */
-#define IRQ_WAITING             0x00200000      /* IRQ not yet seen - for autodetection */
-#define IRQ_LEVEL               0x00400000      /* IRQ level triggered */
-#define IRQ_MASKED              0x00800000      /* IRQ masked - shouldn't be seen again */
-#define IRQ_PER_CPU             0x01000000      /* IRQ is per CPU */
+#define IRQ_INPROGRESS          0x00000100      /* IRQ handler active - do not enter! */
+#define IRQ_DISABLED            0x00000200      /* IRQ disabled - do not enter! */
+#define IRQ_PENDING             0x00000400      /* IRQ pending - replay on enable */
+#define IRQ_REPLAY              0x00000800      /* IRQ has been replayed but not acked yet */
+#define IRQ_AUTODETECT          0x00001000      /* IRQ is being autodetected */
+#define IRQ_WAITING             0x00002000      /* IRQ not yet seen - for autodetection */
+#define IRQ_LEVEL               0x00004000      /* IRQ level triggered */
+#define IRQ_MASKED              0x00008000      /* IRQ masked - shouldn't be seen again */
+#define IRQ_PER_CPU             0x00010000      /* IRQ is per CPU */
+#define IRQ_NOPROBE             0x00020000      /* IRQ is not valid for probing */
+#define IRQ_NOREQUEST           0x00040000      /* IRQ cannot be requested */
+#define IRQ_NOAUTOEN            0x00080000      /* IRQ will not be enabled on request irq */
+#define IRQ_DELAYED_DISABLE     0x00100000      /* IRQ disable (masking) happens delayed. */
+#define IRQ_WAKEUP              0x00200000      /* IRQ triggers system wakeup */
+#define IRQ_MOVE_PENDING        0x00400000      /* need to re-target IRQ destination */
+#define IRQ_NO_BALANCING        0x00800000      /* IRQ is excluded from balancing */
+
 #ifdef CONFIG_IRQ_PER_CPU
 # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU)
+# define IRQ_NO_BALANCING_MASK  (IRQ_PER_CPU | IRQ_NO_BALANCING)
 #else
 # define CHECK_IRQ_PER_CPU(var) 0
+# define IRQ_NO_BALANCING_MASK  IRQ_NO_BALANCING
 #endif
 
-#define IRQ_NOPROBE             0x02000000      /* IRQ is not valid for probing */
-#define IRQ_NOREQUEST           0x04000000      /* IRQ cannot be requested */
-#define IRQ_NOAUTOEN            0x08000000      /* IRQ will not be enabled on request irq */
-#define IRQ_DELAYED_DISABLE     0x10000000      /* IRQ disable (masking) happens delayed. */
-#define IRQ_WAKEUP              0x20000000      /* IRQ triggers system wakeup */
-#define IRQ_MOVE_PENDING        0x40000000      /* need to re-target IRQ destination */
-
 struct proc_dir_entry;
 struct msi_desc;
 
@@ -261,6 +264,11 @@ static inline int select_smp_affinity(unsigned int irq)
 
 extern int no_irq_affinity;
 
+static inline int irq_balancing_disabled(unsigned int irq)
+{
+        return irq_desc[irq].status & IRQ_NO_BALANCING_MASK;
+}
+
 /* Handle irq action chains: */
 extern int handle_IRQ_event(unsigned int irq, struct irqaction *action);
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index acc5d9fe462b..cd790ad0ae57 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -281,6 +281,10 @@ int setup_irq(unsigned int irq, struct irqaction *new)
         if (new->flags & IRQF_PERCPU)
                 desc->status |= IRQ_PER_CPU;
 #endif
+        /* Exclude IRQ from balancing */
+        if (new->flags & IRQF_NOBALANCING)
+                desc->status |= IRQ_NO_BALANCING;
+
         if (!shared) {
                 irq_chip_set_defaults(desc->chip);
 
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 6d3be06e8ce6..bb44bc995d6e 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -55,7 +55,7 @@ static int irq_affinity_write_proc(struct file *file, const char __user *buffer,
         cpumask_t new_value, tmp;
 
         if (!irq_desc[irq].chip->set_affinity || no_irq_affinity ||
-                                CHECK_IRQ_PER_CPU(irq_desc[irq].status))
+            irq_balancing_disabled(irq))
                 return -EIO;
 
         err = cpumask_parse_user(buffer, count, new_value);