parisc: implement irq stacks - part 2 (v2)

This patch fixes few build issues which were introduced with the last
irq stack patch, e.g. the combination of stack overflow check and irq
stack.

Furthermore we now do proper locking and change the irq bh handler
to use the irq stack as well.

In /proc/interrupts one now can monitor how huge the irq stack has grown
and how often it was preferred over the kernel stack.

IRQ stacks are now enabled by default just to make sure that we not
overflow the kernel stack by accident.

Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/include/asm/hardirq.h

@@ -11,10 +11,18 @@
 #include <linux/threads.h>
 #include <linux/irq.h>
 
+#ifdef CONFIG_IRQSTACKS
+#define __ARCH_HAS_DO_SOFTIRQ
+#endif
+
 typedef struct {
 	unsigned int __softirq_pending;
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 	unsigned int kernel_stack_usage;
+#ifdef CONFIG_IRQSTACKS
+	unsigned int irq_stack_usage;
+	unsigned int irq_stack_counter;
+#endif
 #endif
 #ifdef CONFIG_SMP
 	unsigned int irq_resched_count;
@@ -28,6 +36,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
 #define __ARCH_IRQ_STAT
 #define __IRQ_STAT(cpu, member) (irq_stat[cpu].member)
 #define inc_irq_stat(member)	this_cpu_inc(irq_stat.member)
+#define __inc_irq_stat(member)	__this_cpu_inc(irq_stat.member)
 #define local_softirq_pending()	this_cpu_read(irq_stat.__softirq_pending)
 
 #define __ARCH_SET_SOFTIRQ_PENDING

arch/parisc/include/asm/processor.h

@@ -63,10 +63,13 @@
  */
 #ifdef __KERNEL__
 
+#include <linux/spinlock_types.h>
+
 #define IRQ_STACK_SIZE      (4096 << 2) /* 16k irq stack size */
 
 union irq_stack_union {
 	unsigned long stack[IRQ_STACK_SIZE/sizeof(unsigned long)];
+	raw_spinlock_t lock;
 };
 
 DECLARE_PER_CPU(union irq_stack_union, irq_stack_union);