[PATCH] genirq: do not mask interrupts by default

Never mask interrupts immediately upon request.  Disabling interrupts in
high-performance codepaths is rare, and on the other hand this change could
recover lost edges (or even other types of lost interrupts) by conservatively
only masking interrupts after they happen.  (NOTE: with this change the
highlevel irq-disable code still soft-disables this IRQ line - and if such an
interrupt happens then the IRQ flow handler keeps the IRQ masked.)

Mark i8529A controllers as 'never loses an edge'.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/kernel/i8259.c b/arch/i386/kernel/i8259.c
index 255b1af9a0549ff91f4d0f7c94e1569009956fd2..03abfdb1a6e4c5cb8e4c7e407f0a19e3763de2df 100644 (file)
--- a/arch/i386/kernel/i8259.c
+++ b/arch/i386/kernel/i8259.c
@@ -41,6 +41,7 @@ static void mask_and_ack_8259A(unsigned int);
 static struct irq_chip i8259A_chip = {
        .name           = "XT-PIC",
        .mask           = disable_8259A_irq,
+       .disable        = disable_8259A_irq,
        .unmask         = enable_8259A_irq,
        .mask_ack       = mask_and_ack_8259A,
 };

diff --git a/arch/x86_64/kernel/i8259.c b/arch/x86_64/kernel/i8259.c
index d73c79e821f172ee3efe48f490e97b947bb8c153..01e2cf0bdeb10a60bbfb967d9dae2880b2f9827f 100644 (file)
--- a/arch/x86_64/kernel/i8259.c
+++ b/arch/x86_64/kernel/i8259.c
@@ -103,6 +103,7 @@ static void mask_and_ack_8259A(unsigned int);
 static struct irq_chip i8259A_chip = {
        .name           = "XT-PIC",
        .mask           = disable_8259A_irq,
+       .disable        = disable_8259A_irq,
        .unmask         = enable_8259A_irq,
        .mask_ack       = mask_and_ack_8259A,
 };

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 475e8a71bcdc19772b312461b95ba0b171f1790e..76a9106a0bf4ad2a7a7d5805e1fc00c94522b696 100644 (file)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -230,10 +230,6 @@ static void default_enable(unsigned int irq)
  */
 static void default_disable(unsigned int irq)
 {
-       struct irq_desc *desc = irq_desc + irq;
-
-       if (!(desc->status & IRQ_DELAYED_DISABLE))
-               desc->chip->mask(irq);
 }
 
 /*
@@ -298,13 +294,18 @@ handle_simple_irq(unsigned int irq, struct irq_desc *desc)
 
        if (unlikely(desc->status & IRQ_INPROGRESS))
                goto out_unlock;
-       desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_cpu(cpu).irqs[irq]++;
 
        action = desc->action;
-       if (unlikely(!action || (desc->status & IRQ_DISABLED)))
+       if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
+               if (desc->chip->mask)
+                       desc->chip->mask(irq);
+               desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
+               desc->status |= IRQ_PENDING;
                goto out_unlock;
+       }
 
+       desc->status &= ~(IRQ_REPLAY | IRQ_WAITING | IRQ_PENDING);
        desc->status |= IRQ_INPROGRESS;
        spin_unlock(&desc->lock);
 
@@ -396,11 +397,13 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
 
        /*
         * If its disabled or no action available
-        * keep it masked and get out of here
+        * then mask it and get out of here:
         */
        action = desc->action;
        if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
                desc->status |= IRQ_PENDING;
+               if (desc->chip->mask)
+                       desc->chip->mask(irq);
                goto out;
        }