[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>

1 files changed, 0 insertions, 5 deletions

diff --git a/drivers/pci/msi.h b/drivers/pci/msi.h
index 390f1851c0f1..402136a5c9e4 100644
--- a/drivers/pci/msi.h
+++ b/drivers/pci/msi.h
@@ -19,7 +19,6 @@
 #define NR_HP_RESERVED_VECTORS  20
 
 extern int vector_irq[NR_VECTORS];
-extern cpumask_t pending_irq_balance_cpumask[NR_IRQS];
 extern void (*interrupt[NR_IRQS])(void);
 extern int pci_vector_resources(int last, int nr_released);
 
@@ -29,10 +28,6 @@ extern int pci_vector_resources(int last, int nr_released);
 #define set_msi_irq_affinity    NULL
 #endif
 
-#ifndef CONFIG_IRQBALANCE
-static inline void move_msi(int vector) {}
-#endif
-
 /*
  * MSI-X Address Register
  */