[PATCH] Re: softirq buggy

[Manfred Spraul]

I've attached a new patch:

* cpu_is_idle() moved to <linux/pm.h>
* function uninlined due to header dependencies
* cpu_is_idle() doesn't call do_softirq directly, instead the caller
returns to schedule()
* cpu_is_idle() exported for modules.
* docu updated.

I'd prefer to inline cpu_is_idle(), but optimizing the idle code path is
probably not that important ;-)

--
        Manfred
// $Header$
// Kernel Version:
//  VERSION = 2
//  PATCHLEVEL = 4
//  SUBLEVEL = 3
//  EXTRAVERSION = -ac3
--- 2.4/include/linux/pm.h      Thu Jan  4 23:50:47 2001
+++ build-2.4/include/linux/pm.h        Sun Apr  8 21:02:02 2001
@@ -186,6 +186,8 @@
 extern void (*pm_idle)(void);
 extern void (*pm_power_off)(void);
 
+int cpu_is_idle(void);
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_PM_H */
--- 2.4/kernel/sched.c  Sat Apr  7 22:02:27 2001
+++ build-2.4/kernel/sched.c    Sun Apr  8 21:02:37 2001
@@ -1242,6 +1242,28 @@
        sched_data->last_schedule = get_cycles();
 }
 
+/**
+ * cpu_is_idle - helper function for idle functions
+ * 
+ * pm_idle functions must call this function to verify that
+ * the cpu is really idle.
+ * The return value is valid until local interrupts are
+ * reenabled.
+ * Return values:
+ * 1: go into power saving mode.
+ * 0: cpu is not idle, return to schedule()
+ */
+int cpu_is_idle(void)
+{
+       if (current->need_resched)
+               return 0;
+
+       if (softirq_active(smp_processor_id()) & softirq_mask(smp_processor_id()))
+               return 0;
+
+       return 1;
+}
+
 extern void init_timervecs (void);
 
 void __init sched_init(void)
--- 2.4/kernel/ksyms.c  Sat Apr  7 22:02:27 2001
+++ build-2.4/kernel/ksyms.c    Sun Apr  8 21:42:48 2001
@@ -440,6 +440,7 @@
 #endif
 EXPORT_SYMBOL(kstat);
 EXPORT_SYMBOL(nr_running);
+EXPORT_SYMBOL(cpu_is_idle);
 
 /* misc */
 EXPORT_SYMBOL(panic);
--- 2.4/arch/i386/kernel/process.c      Thu Feb 22 22:28:52 2001
+++ build-2.4/arch/i386/kernel/process.c        Sun Apr  8 21:25:23 2001
@@ -81,7 +81,7 @@
 {
        if (current_cpu_data.hlt_works_ok && !hlt_counter) {
                __cli();
-               if (!current->need_resched)
+               if (cpu_is_idle())
                        safe_halt();
                else
                        __sti();
@@ -105,13 +105,10 @@
         */
        oldval = xchg(&current->need_resched, -1);
 
-       if (!oldval)
-               asm volatile(
-                       "2:"
-                       "cmpl $-1, %0;"
-                       "rep; nop;"
-                       "je 2b;"
-                               : :"m" (current->need_resched));
+       if (!oldval) {
+               while(cpu_is_idle())
+                       rep_nop();
+       }
 }
 
 /*
@@ -131,7 +128,7 @@
                void (*idle)(void) = pm_idle;
                if (!idle)
                        idle = default_idle;
-               while (!current->need_resched)
+               while (cpu_is_idle())
                        idle();
                schedule();
                check_pgt_cache();
--- 2.4/drivers/acpi/cpu.c      Sat Apr  7 22:02:01 2001
+++ build-2.4/drivers/acpi/cpu.c        Sat Apr  7 23:55:17 2001
@@ -148,7 +148,7 @@
                unsigned long diff;
                
                __cli();
-               if (current->need_resched)
+               if (!cpu_is_idle())
                        goto out;
                if (acpi_bm_activity())
                        goto sleep2;
@@ -171,7 +171,7 @@
                unsigned long diff;
 
                __cli();
-               if (current->need_resched)
+               if (!cpu_is_idle())
                        goto out;
                if (acpi_bm_activity())
                        goto sleep2;
@@ -205,7 +205,7 @@
                unsigned long diff;
 
                __cli();
-               if (current->need_resched)
+               if (!cpu_is_idle())
                        goto out;
 
                time = acpi_read_pm_timer();
@@ -235,7 +235,7 @@
                unsigned long diff;
 
                __cli();
-               if (current->need_resched)
+               if (!cpu_is_idle())
                        goto out;
                time = acpi_read_pm_timer();
                acpi_c1_count++;