From 7f424a8b08c26dc14ac5c17164014539ac9a5c65 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 25 Apr 2008 17:39:01 +0200 Subject: fix idle (arch, acpi and apm) and lockdep OK, so 25-mm1 gave a lockdep error which made me look into this. The first thing that I noticed was the horrible mess; the second thing I saw was hacks like: 71e93d15612c61c2e26a169567becf088e71b8ff The problem is that arch idle routines are somewhat inconsitent with their IRQ state handling and instead of fixing _that_, we go paper over the problem. So the thing I've tried to do is set a standard for idle routines and fix them all up to adhere to that. So the rules are: idle routines are entered with IRQs disabled idle routines will exit with IRQs enabled Nearly all already did this in one form or another. Merge the 32 and 64 bit bits so they no longer have different bugs. As for the actual lockdep warning; __sti_mwait() did a plainly un-annotated irq-enable. Signed-off-by: Peter Zijlstra Tested-by: Bob Copeland Signed-off-by: Ingo Molnar --- arch/x86/kernel/process_32.c | 118 ++----------------------------------------- 1 file changed, 4 insertions(+), 114 deletions(-) (limited to 'arch/x86/kernel/process_32.c') diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 77de848bd1f..f8476dfbb60 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -111,12 +111,10 @@ void default_idle(void) */ smp_mb(); - local_irq_disable(); - if (!need_resched()) { + if (!need_resched()) safe_halt(); /* enables interrupts racelessly */ - local_irq_disable(); - } - local_irq_enable(); + else + local_irq_enable(); current_thread_info()->status |= TS_POLLING; } else { local_irq_enable(); @@ -128,17 +126,6 @@ void default_idle(void) EXPORT_SYMBOL(default_idle); #endif -/* - * On SMP it's slightly faster (but much more power-consuming!) - * to poll the ->work.need_resched flag instead of waiting for the - * cross-CPU IPI to arrive. Use this option with caution. - */ -static void poll_idle(void) -{ - local_irq_enable(); - cpu_relax(); -} - #ifdef CONFIG_HOTPLUG_CPU #include /* We don't actually take CPU down, just spin without interrupts. */ @@ -196,6 +183,7 @@ void cpu_idle(void) if (cpu_is_offline(cpu)) play_dead(); + local_irq_disable(); __get_cpu_var(irq_stat).idle_timestamp = jiffies; idle(); } @@ -206,104 +194,6 @@ void cpu_idle(void) } } -static void do_nothing(void *unused) -{ -} - -/* - * cpu_idle_wait - Used to ensure that all the CPUs discard old value of - * pm_idle and update to new pm_idle value. Required while changing pm_idle - * handler on SMP systems. - * - * Caller must have changed pm_idle to the new value before the call. Old - * pm_idle value will not be used by any CPU after the return of this function. - */ -void cpu_idle_wait(void) -{ - smp_mb(); - /* kick all the CPUs so that they exit out of pm_idle */ - smp_call_function(do_nothing, NULL, 0, 1); -} -EXPORT_SYMBOL_GPL(cpu_idle_wait); - -/* - * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, - * which can obviate IPI to trigger checking of need_resched. - * We execute MONITOR against need_resched and enter optimized wait state - * through MWAIT. Whenever someone changes need_resched, we would be woken - * up from MWAIT (without an IPI). - * - * New with Core Duo processors, MWAIT can take some hints based on CPU - * capability. - */ -void mwait_idle_with_hints(unsigned long ax, unsigned long cx) -{ - if (!need_resched()) { - __monitor((void *)¤t_thread_info()->flags, 0, 0); - smp_mb(); - if (!need_resched()) - __sti_mwait(ax, cx); - else - local_irq_enable(); - } else - local_irq_enable(); -} - -/* Default MONITOR/MWAIT with no hints, used for default C1 state */ -static void mwait_idle(void) -{ - local_irq_enable(); - mwait_idle_with_hints(0, 0); -} - -static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c) -{ - if (force_mwait) - return 1; - /* Any C1 states supported? */ - return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0; -} - -void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) -{ - static int selected; - - if (selected) - return; -#ifdef CONFIG_X86_SMP - if (pm_idle == poll_idle && smp_num_siblings > 1) { - printk(KERN_WARNING "WARNING: polling idle and HT enabled," - " performance may degrade.\n"); - } -#endif - if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { - /* - * Skip, if setup has overridden idle. - * One CPU supports mwait => All CPUs supports mwait - */ - if (!pm_idle) { - printk(KERN_INFO "using mwait in idle threads.\n"); - pm_idle = mwait_idle; - } - } - selected = 1; -} - -static int __init idle_setup(char *str) -{ - if (!strcmp(str, "poll")) { - printk("using polling idle threads.\n"); - pm_idle = poll_idle; - } else if (!strcmp(str, "mwait")) - force_mwait = 1; - else - return -1; - - boot_option_idle_override = 1; - return 0; -} -early_param("idle", idle_setup); - void __show_registers(struct pt_regs *regs, int all) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; -- cgit v1.2.3-70-g09d2