[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, 69 insertions, 38 deletions

diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 75e52c57f19c..251ce7cf1a38 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -441,6 +441,11 @@ config ISA_DMA_API
         bool
         default y
 
+config GENERIC_PENDING_IRQ
+        bool
+        depends on GENERIC_HARDIRQS && SMP
+        default y
+
 menu "Power management options"
 
 source kernel/power/Kconfig
diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index d206d7e49cf5..76bcc4e6979d 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -78,6 +78,54 @@ int vector_irq[NR_VECTORS] = { [0 ... NR_VECTORS - 1] = -1};
 #define vector_to_irq(vector)   (vector)
 #endif
 
+#define __DO_ACTION(R, ACTION, FINAL)                                   \
+                                                                        \
+{                                                                       \
+        int pin;                                                        \
+        struct irq_pin_list *entry = irq_2_pin + irq;                   \
+                                                                        \
+        for (;;) {                                                      \
+                unsigned int reg;                                       \
+                pin = entry->pin;                                       \
+                if (pin == -1)                                          \
+                        break;                                          \
+                reg = io_apic_read(entry->apic, 0x10 + R + pin*2);      \
+                reg ACTION;                                             \
+                io_apic_modify(entry->apic, reg);                       \
+                if (!entry->next)                                       \
+                        break;                                          \
+                entry = irq_2_pin + entry->next;                        \
+        }                                                               \
+        FINAL;                                                          \
+}
+
+#ifdef CONFIG_SMP
+static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t mask)
+{
+        unsigned long flags;
+        unsigned int dest;
+        cpumask_t tmp;
+
+        cpus_and(tmp, mask, cpu_online_map);
+        if (cpus_empty(tmp))
+                tmp = TARGET_CPUS;
+
+        cpus_and(mask, tmp, CPU_MASK_ALL);
+
+        dest = cpu_mask_to_apicid(mask);
+
+        /*
+         * Only the high 8 bits are valid.
+         */
+        dest = SET_APIC_LOGICAL_ID(dest);
+
+        spin_lock_irqsave(&ioapic_lock, flags);
+        __DO_ACTION(1, = dest, )
+        set_irq_info(irq, mask);
+        spin_unlock_irqrestore(&ioapic_lock, flags);
+}
+#endif
+
 /*
  * The common case is 1:1 IRQ<->pin mappings. Sometimes there are
  * shared ISA-space IRQs, so we have to support them. We are super
@@ -101,26 +149,6 @@ static void add_pin_to_irq(unsigned int irq, int apic, int pin)
         entry->pin = pin;
 }
 
-#define __DO_ACTION(R, ACTION, FINAL)                                   \
-                                                                        \
-{                                                                       \
-        int pin;                                                        \
-        struct irq_pin_list *entry = irq_2_pin + irq;                   \
-                                                                        \
-        for (;;) {                                                      \
-                unsigned int reg;                                       \
-                pin = entry->pin;                                       \
-                if (pin == -1)                                          \
-                        break;                                          \
-                reg = io_apic_read(entry->apic, 0x10 + R + pin*2);      \
-                reg ACTION;                                             \
-                io_apic_modify(entry->apic, reg);                       \
-                if (!entry->next)                                       \
-                        break;                                          \
-                entry = irq_2_pin + entry->next;                        \
-        }                                                               \
-        FINAL;                                                          \
-}
 
 #define DO_ACTION(name,R,ACTION, FINAL)                                 \
                                                                         \
@@ -767,6 +795,7 @@ static void __init setup_IO_APIC_irqs(void)
                 spin_lock_irqsave(&ioapic_lock, flags);
                 io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
                 io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
+                set_native_irq_info(irq, TARGET_CPUS);
                 spin_unlock_irqrestore(&ioapic_lock, flags);
         }
         }
@@ -1314,6 +1343,7 @@ static unsigned int startup_edge_ioapic_irq(unsigned int irq)
  */
 static void ack_edge_ioapic_irq(unsigned int irq)
 {
+        move_irq(irq);
         if ((irq_desc[irq].status & (IRQ_PENDING | IRQ_DISABLED))
                                         == (IRQ_PENDING | IRQ_DISABLED))
                 mask_IO_APIC_irq(irq);
@@ -1343,26 +1373,10 @@ static unsigned int startup_level_ioapic_irq (unsigned int irq)
 
 static void end_level_ioapic_irq (unsigned int irq)
 {
+        move_irq(irq);
         ack_APIC_irq();
 }
 
-static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t mask)
-{
-        unsigned long flags;
-        unsigned int dest;
-
-        dest = cpu_mask_to_apicid(mask);
-
-        /*
-         * Only the high 8 bits are valid.
-         */
-        dest = SET_APIC_LOGICAL_ID(dest);
-
-        spin_lock_irqsave(&ioapic_lock, flags);
-        __DO_ACTION(1, = dest, )
-        spin_unlock_irqrestore(&ioapic_lock, flags);
-}
-
 #ifdef CONFIG_PCI_MSI
 static unsigned int startup_edge_ioapic_vector(unsigned int vector)
 {
@@ -1375,6 +1389,7 @@ static void ack_edge_ioapic_vector(unsigned int vector)
 {
         int irq = vector_to_irq(vector);
 
+        move_native_irq(vector);
         ack_edge_ioapic_irq(irq);
 }
 
@@ -1389,6 +1404,7 @@ static void end_level_ioapic_vector (unsigned int vector)
 {
         int irq = vector_to_irq(vector);
 
+        move_native_irq(vector);
         end_level_ioapic_irq(irq);
 }
 
@@ -1406,14 +1422,17 @@ static void unmask_IO_APIC_vector (unsigned int vector)
         unmask_IO_APIC_irq(irq);
 }
 
+#ifdef CONFIG_SMP
 static void set_ioapic_affinity_vector (unsigned int vector,
                                         cpumask_t cpu_mask)
 {
         int irq = vector_to_irq(vector);
 
+        set_native_irq_info(vector, cpu_mask);
         set_ioapic_affinity_irq(irq, cpu_mask);
 }
-#endif
+#endif // CONFIG_SMP
+#endif // CONFIG_PCI_MSI
 
 /*
  * Level and edge triggered IO-APIC interrupts need different handling,
@@ -1432,7 +1451,9 @@ static struct hw_interrupt_type ioapic_edge_type = {
         .disable        = disable_edge_ioapic,
         .ack            = ack_edge_ioapic,
         .end            = end_edge_ioapic,
+#ifdef CONFIG_SMP
         .set_affinity = set_ioapic_affinity,
+#endif
 };
 
 static struct hw_interrupt_type ioapic_level_type = {
@@ -1443,7 +1464,9 @@ static struct hw_interrupt_type ioapic_level_type = {
         .disable        = disable_level_ioapic,
         .ack            = mask_and_ack_level_ioapic,
         .end            = end_level_ioapic,
+#ifdef CONFIG_SMP
         .set_affinity = set_ioapic_affinity,
+#endif
 };
 
 static inline void init_IO_APIC_traps(void)
@@ -1918,6 +1941,7 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
         spin_lock_irqsave(&ioapic_lock, flags);
         io_apic_write(ioapic, 0x11+2*pin, *(((int *)&entry)+1));
         io_apic_write(ioapic, 0x10+2*pin, *(((int *)&entry)+0));
+        set_native_irq_info(use_pci_vector() ?  entry.vector : irq, TARGET_CPUS);
         spin_unlock_irqrestore(&ioapic_lock, flags);
 
         return 0;
@@ -1931,6 +1955,7 @@ int io_apic_set_pci_routing (int ioapic, int pin, int irq, int edge_level, int a
  * we need to reprogram the ioredtbls to cater for the cpus which have come online
  * so mask in all cases should simply be TARGET_CPUS
  */
+#ifdef CONFIG_SMP
 void __init setup_ioapic_dest(void)
 {
         int pin, ioapic, irq, irq_entry;
@@ -1949,3 +1974,4 @@ void __init setup_ioapic_dest(void)
 
         }
 }
+#endif