[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, 5 insertions, 12 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 2b85aa39f954..532f73bb2224 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -91,6 +91,7 @@ static void set_msi_affinity(unsigned int vector, cpumask_t cpu_mask)
 {
         struct msi_desc *entry;
         struct msg_address address;
+        unsigned int irq = vector;
 
         entry = (struct msi_desc *)msi_desc[vector];
         if (!entry || !entry->dev)
@@ -112,6 +113,7 @@ static void set_msi_affinity(unsigned int vector, cpumask_t cpu_mask)
                 entry->msi_attrib.current_cpu = cpu_mask_to_apicid(cpu_mask);
                 pci_write_config_dword(entry->dev, msi_lower_address_reg(pos),
                         address.lo_address.value);
+                set_native_irq_info(irq, cpu_mask);
                 break;
         }
         case PCI_CAP_ID_MSIX:
@@ -125,22 +127,13 @@ static void set_msi_affinity(unsigned int vector, cpumask_t cpu_mask)
                         MSI_TARGET_CPU_SHIFT);
                 entry->msi_attrib.current_cpu = cpu_mask_to_apicid(cpu_mask);
                 writel(address.lo_address.value, entry->mask_base + offset);
+                set_native_irq_info(irq, cpu_mask);
                 break;
         }
         default:
                 break;
         }
 }
-
-#ifdef CONFIG_IRQBALANCE
-static inline void move_msi(int vector)
-{
-        if (!cpus_empty(pending_irq_balance_cpumask[vector])) {
-                set_msi_affinity(vector, pending_irq_balance_cpumask[vector]);
-                cpus_clear(pending_irq_balance_cpumask[vector]);
-        }
-}
-#endif /* CONFIG_IRQBALANCE */
 #endif /* CONFIG_SMP */
 
 static void mask_MSI_irq(unsigned int vector)
@@ -191,13 +184,13 @@ static void shutdown_msi_irq(unsigned int vector)
 
 static void end_msi_irq_wo_maskbit(unsigned int vector)
 {
-        move_msi(vector);
+        move_native_irq(vector);
         ack_APIC_irq();
 }
 
 static void end_msi_irq_w_maskbit(unsigned int vector)
 {
-        move_msi(vector);
+        move_native_irq(vector);
         unmask_MSI_irq(vector);
         ack_APIC_irq();
 }