Messages in this thread Patch in this message | | | Date | Fri, 15 Jun 2012 14:49:04 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [RFC patch V2 4/7] softirq: Use hotplug thread infrastructure |
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On Fri, Jun 15, 2012 at 02:13:22PM -0000, Thomas Gleixner wrote: > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
And I got the following build errors on !SMP:
kernel/built-in.o: In function `run_ksoftirqd': /usr/local/autobench/var/tmp/build/kernel/softirq.c:739: undefined reference to `.smpboot_thread_check_parking' kernel/built-in.o: In function `watchdog': /usr/local/autobench/var/tmp/build/kernel/watchdog.c:383: undefined reference to `.smpboot_thread_check_parking' kernel/built-in.o: In function `spawn_ksoftirqd': /usr/local/autobench/var/tmp/build/kernel/softirq.c:853: undefined reference to `.smpboot_register_percpu_thread' kernel/built-in.o: In function `lockup_detector_init': /usr/local/autobench/var/tmp/build/kernel/watchdog.c:514: undefined reference to `.smpboot_register_percpu_thread'
My guess is that !SMP needs empty definitions of these functions.
Thanx, Paul
> --- > kernel/softirq.c | 84 +++++++++++-------------------------------------------- > 1 file changed, 18 insertions(+), 66 deletions(-) > > Index: tip/kernel/softirq.c > =================================================================== > --- tip.orig/kernel/softirq.c > +++ tip/kernel/softirq.c > @@ -23,6 +23,7 @@ > #include <linux/rcupdate.h> > #include <linux/ftrace.h> > #include <linux/smp.h> > +#include <linux/smpboot.h> > #include <linux/tick.h> > > #define CREATE_TRACE_POINTS > @@ -733,24 +734,17 @@ void __init softirq_init(void) > open_softirq(HI_SOFTIRQ, tasklet_hi_action); > } > > -static int run_ksoftirqd(void * __bind_cpu) > +static int run_ksoftirqd(void *td) > { > - set_current_state(TASK_INTERRUPTIBLE); > - > - while (!kthread_should_stop()) { > + while (!smpboot_thread_check_parking(td)) { > + set_current_state(TASK_INTERRUPTIBLE); > preempt_disable(); > - if (!local_softirq_pending()) { > + if (!local_softirq_pending()) > schedule_preempt_disabled(); > - } > > __set_current_state(TASK_RUNNING); > > while (local_softirq_pending()) { > - /* Preempt disable stops cpu going offline. > - If already offline, we'll be on wrong CPU: > - don't process */ > - if (cpu_is_offline((long)__bind_cpu)) > - goto wait_to_die; > local_irq_disable(); > if (local_softirq_pending()) > __do_softirq(); > @@ -758,23 +752,10 @@ static int run_ksoftirqd(void * __bind_c > sched_preempt_enable_no_resched(); > cond_resched(); > preempt_disable(); > - rcu_note_context_switch((long)__bind_cpu); > + rcu_note_context_switch(smp_processor_id()); > } > preempt_enable(); > - set_current_state(TASK_INTERRUPTIBLE); > } > - __set_current_state(TASK_RUNNING); > - return 0; > - > -wait_to_die: > - preempt_enable(); > - /* Wait for kthread_stop */ > - set_current_state(TASK_INTERRUPTIBLE); > - while (!kthread_should_stop()) { > - schedule(); > - set_current_state(TASK_INTERRUPTIBLE); > - } > - __set_current_state(TASK_RUNNING); > return 0; > } > > @@ -841,50 +822,17 @@ static int __cpuinit cpu_callback(struct > unsigned long action, > void *hcpu) > { > - int hotcpu = (unsigned long)hcpu; > - struct task_struct *p; > - > switch (action) { > - case CPU_UP_PREPARE: > - case CPU_UP_PREPARE_FROZEN: > - p = kthread_create_on_node(run_ksoftirqd, > - hcpu, > - cpu_to_node(hotcpu), > - "ksoftirqd/%d", hotcpu); > - if (IS_ERR(p)) { > - printk("ksoftirqd for %i failed\n", hotcpu); > - return notifier_from_errno(PTR_ERR(p)); > - } > - kthread_bind(p, hotcpu); > - per_cpu(ksoftirqd, hotcpu) = p; > - break; > - case CPU_ONLINE: > - case CPU_ONLINE_FROZEN: > - wake_up_process(per_cpu(ksoftirqd, hotcpu)); > - break; > #ifdef CONFIG_HOTPLUG_CPU > - case CPU_UP_CANCELED: > - case CPU_UP_CANCELED_FROZEN: > - if (!per_cpu(ksoftirqd, hotcpu)) > - break; > - /* Unbind so it can run. Fall thru. */ > - kthread_bind(per_cpu(ksoftirqd, hotcpu), > - cpumask_any(cpu_online_mask)); > case CPU_DEAD: > case CPU_DEAD_FROZEN: { > - static const struct sched_param param = { > - .sched_priority = MAX_RT_PRIO-1 > - }; > - > - p = per_cpu(ksoftirqd, hotcpu); > - per_cpu(ksoftirqd, hotcpu) = NULL; > - sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); > - kthread_stop(p); > + int hotcpu = (unsigned long)hcpu; > + > takeover_tasklets(hotcpu); > break; > } > #endif /* CONFIG_HOTPLUG_CPU */ > - } > + } > return NOTIFY_OK; > } > > @@ -892,14 +840,18 @@ static struct notifier_block __cpuinitda > .notifier_call = cpu_callback > }; > > +static struct smp_hotplug_thread softirq_threads = { > + .store = &ksoftirqd, > + .thread_fn = run_ksoftirqd, > + .thread_comm = "ksoftirqd/%u", > +}; > + > static __init int spawn_ksoftirqd(void) > { > - void *cpu = (void *)(long)smp_processor_id(); > - int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); > - > - BUG_ON(err != NOTIFY_OK); > - cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); > register_cpu_notifier(&cpu_nfb); > + > + BUG_ON(smpboot_register_percpu_thread(&softirq_threads)); > + > return 0; > } > early_initcall(spawn_ksoftirqd); > >
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