[PATCH] irq_cpustat cleanup

From: Christoph Hellwig <hch@lst.de>

currently only x86_64 and ia64 don't use the generic irq_cpustat code
and both have to workaround it's brokenness for the non-default case.

x86_64 defines an empty irq_cpustat_t even if it doesn't need one and
ia64 adds CONFIG_IA64 ifdefs around all users.  What about this patch
instead to make __ARCH_IRQ_STAT useable?

include/asm-ia64/hardirq.h

@@ -16,6 +16,9 @@
 /*
  * No irq_cpustat_t for IA-64.  The data is held in the per-CPU data structure.
  */
+
+#define __ARCH_IRQ_STAT	1
+
 #define softirq_pending(cpu)		(cpu_data(cpu)->softirq_pending)
 #define syscall_count(cpu)		/* unused on IA-64 */
 #define ksoftirqd_task(cpu)		(cpu_data(cpu)->ksoftirqd)

include/asm-x86_64/hardirq.h

@@ -12,10 +12,6 @@
    special access macros. This would generate better code. */ 
 #define __IRQ_STAT(cpu,member) (read_pda(me)->member)
 
-typedef struct {
-	/* Empty. All the fields have moved to the PDA. */
-} irq_cpustat_t; 
-
 #include <linux/irq_cpustat.h>	/* Standard mappings for irq_cpustat_t above */
 
 /*

include/linux/irq_cpustat.h

@@ -17,9 +17,8 @@
  * definitions instead of differing sets for each arch.
  */
 
-extern irq_cpustat_t irq_stat[];			/* defined in asm/hardirq.h */
-
-#ifndef __ARCH_IRQ_STAT /* Some architectures can do this more efficiently */ 
+#ifndef __ARCH_IRQ_STAT
+extern irq_cpustat_t irq_stat[];		/* defined in asm/hardirq.h */
 #ifdef CONFIG_SMP
 #define __IRQ_STAT(cpu, member)	(irq_stat[cpu].member)
 #else
@@ -31,8 +30,11 @@ extern irq_cpustat_t irq_stat[];			/* defined in asm/hardirq.h */
 #define softirq_pending(cpu)	__IRQ_STAT((cpu), __softirq_pending)
 #define local_softirq_pending()	softirq_pending(smp_processor_id())
 #define syscall_count(cpu)	__IRQ_STAT((cpu), __syscall_count)
+#define local_syscall_count()	syscall_count(smp_processor_id())
 #define ksoftirqd_task(cpu)	__IRQ_STAT((cpu), __ksoftirqd_task)
+#define local_ksoftirqd_task()	ksoftirqd_task(smp_processor_id())
+
   /* arch dependent irq_stat fields */
-#define nmi_count(cpu)		__IRQ_STAT((cpu), __nmi_count)		/* i386, ia64 */
+#define nmi_count(cpu)		__IRQ_STAT((cpu), __nmi_count)	/* i386 */
 
 #endif	/* __irq_cpustat_h */

kernel/ksyms.c

@@ -403,7 +403,6 @@ EXPORT_SYMBOL(add_timer);
 EXPORT_SYMBOL(del_timer);
 EXPORT_SYMBOL(request_irq);
 EXPORT_SYMBOL(free_irq);
-EXPORT_SYMBOL(irq_stat);
 
 /* waitqueue handling */
 EXPORT_SYMBOL(add_wait_queue);

kernel/softirq.c

@@ -34,7 +34,10 @@
    - Tasklets: serialized wrt itself.
  */
 
+#ifndef __ARCH_IRQ_STAT
 irq_cpustat_t irq_stat[NR_CPUS] ____cacheline_aligned;
+EXPORT_SYMBOL(irq_stat);
+#endif
 
 static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp;
 
@@ -322,7 +325,7 @@ static int ksoftirqd(void * __bind_cpu)
 	__set_current_state(TASK_INTERRUPTIBLE);
 	mb();
 
-	ksoftirqd_task(cpu) = current;
+	local_ksoftirqd_task() = current;
 
 	for (;;) {
 		if (!local_softirq_pending())