Re: [PATCH 2/9] irq-remove: arch non-trivial

From: Jeff Garzik
Date: Fri Oct 19 2007 - 13:50:39 EST


Jeremy Fitzhardinge wrote:
Jeff Garzik wrote:
commit 8d45690dd90b18daaa21b981ab20caf393220bf0
Author: Jeff Garzik <jeff@xxxxxxxxxx>
Date: Fri Oct 19 00:46:23 2007 -0400

[IRQ ARG REMOVAL] various non-trivial arch updates

arch/x86/kernel/vm86_32.c | 3 ++-
include/asm-x86/irq_regs_32.h | 25 +++++++++++++++++++++++++
2 files changed, 27 insertions(+), 1 deletion(-)

8d45690dd90b18daaa21b981ab20caf393220bf0
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 157e4be..18aae9e 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -739,10 +739,11 @@ static int irqbits;
| (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
| (1 << SIGUNUSED) )

-static irqreturn_t irq_handler(int intno, void *dev_id)
+static irqreturn_t irq_handler(void *dev_id)
{
int irq_bit;
unsigned long flags;
+ unsigned int intno = get_irqfunc_irq();
spin_lock_irqsave(&irqbits_lock, flags);
irq_bit = 1 << intno;
diff --git a/include/asm-x86/irq_regs_32.h b/include/asm-x86/irq_regs_32.h
index 3368b20..68a531d 100644
--- a/include/asm-x86/irq_regs_32.h
+++ b/include/asm-x86/irq_regs_32.h
@@ -26,4 +26,29 @@ static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs)
return old_regs;
}
+DECLARE_PER_CPU(unsigned int, __irqfunc_irqs);
+
+static inline unsigned int get_irqfunc_irq(void)
+{
+ return __get_cpu_var(__irqfunc_irqs);
+}
+
+#if 0
+static inline unsigned int set_irqfunc_irq(unsigned int new_irq)
+{
+ unsigned int old_irq, *pirq = &__get_cpu_var(__irqfunc_irqs);
+
+ old_irq = *pirq;
+ *pirq = new_irq;
+ return old_irq;
+}
+#else
+static inline void set_irqfunc_irq(unsigned int new_irq)
+{
+ int *pirq = &__get_cpu_var(__irqfunc_irqs);
+
+ *pirq = new_irq;

x86_write_percpu(__irqfunc_irqs, new_irq) would be slightly more
efficient here. Any why the pointer anyway?

Answering the latter question -- that's the way include/asm-generic/irq_regs.h was written, and I simply followed their lead.

One attribute of this method is to avoid preemption, which is probably necessary in the bowels of irq handling.

Jeff



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