[PATCH] x86/x86_64: deferred handling of writes to /proc/irqxx/smp_affinity

When handling writes to /proc/irq, current code is re-programming rte
entries directly. This is not recommended and could potentially cause
chipset's to lockup, or cause missing interrupts.

CONFIG_IRQ_BALANCE does this correctly, where it re-programs only when the
interrupt is pending. The same needs to be done for /proc/irq handling as well.
Otherwise user space irq balancers are really not doing the right thing.

- Changed pending_irq_balance_cpumask to pending_irq_migrate_cpumask for
  lack of a generic name.
- added move_irq out of IRQ_BALANCE, and added this same to X86_64
- Added new proc handler for write, so we can do deferred write at irq
  handling time.
- Display of /proc/irq/XX/smp_affinity used to display CPU_MASKALL, instead
  it now shows only active cpu masks, or exactly what was set.
- Provided a common move_irq implementation, instead of duplicating
  when using generic irq framework.

Tested on i386/x86_64 and ia64 with CONFIG_PCI_MSI turned on and off.
Tested UP builds as well.

MSI testing: tbd: I have cards, need to look for a x-over cable, although I
did test an earlier version of this patch.  Will test in a couple days.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Acked-by: Zwane Mwaikambo <zwane@holomorphy.com>
Grudgingly-acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Coywolf Qi Hunt <coywolf@lovecn.org>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 0 insertions, 13 deletions

diff --git a/include/asm-ia64/hw_irq.h b/include/asm-ia64/hw_irq.h
index 041ab8c..0cf119b 100644
--- a/include/asm-ia64/hw_irq.h
+++ b/include/asm-ia64/hw_irq.h
@@ -116,13 +116,6 @@ __ia64_local_vector_to_irq (ia64_vector vec)
  * and to obtain the irq descriptor for a given irq number.
  */
 
-/* Return a pointer to the irq descriptor for IRQ.  */
-static inline irq_desc_t *
-irq_descp (int irq)
-{
-	return irq_desc + irq;
-}
-
 /* Extract the IA-64 vector that corresponds to IRQ.  */
 static inline ia64_vector
 irq_to_vector (int irq)
diff --git a/include/asm-ia64/irq.h b/include/asm-ia64/irq.h
index bd07d11..5d930fd 100644
--- a/include/asm-ia64/irq.h
+++ b/include/asm-ia64/irq.h
@@ -30,12 +30,6 @@ extern void disable_irq_nosync (unsigned int);
 extern void enable_irq (unsigned int);
 extern void set_irq_affinity_info (unsigned int irq, int dest, int redir);
 
-#ifdef CONFIG_SMP
-extern void move_irq(int irq);
-#else
-#define move_irq(irq)
-#endif
-
 struct irqaction;
 struct pt_regs;
 int handle_IRQ_event(unsigned int, struct pt_regs *, struct irqaction *);