irq_work: Do not raise an IPI when queueing work on the local CPU
The QEMU PowerPC/PSeries machine model was not expecting a self-IPI, and it may be a bit surprising thing to do, so have irq_work_queue_on do local queueing when target is the current CPU. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= <clg@kaod.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190409093403.20994-1-npiggin@gmail.com [ Simplified the preprocessor comments. Fixed unbalanced curly brackets pointed out by Thomas. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -56,34 +56,18 @@ void __weak arch_irq_work_raise(void)
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*/
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}
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/*
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* Enqueue the irq_work @work on @cpu unless it's already pending
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* somewhere.
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*
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* Can be re-enqueued while the callback is still in progress.
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*/
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bool irq_work_queue_on(struct irq_work *work, int cpu)
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/* Enqueue on current CPU, work must already be claimed and preempt disabled */
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static void __irq_work_queue_local(struct irq_work *work)
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{
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/* All work should have been flushed before going offline */
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WARN_ON_ONCE(cpu_is_offline(cpu));
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#ifdef CONFIG_SMP
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/* Arch remote IPI send/receive backend aren't NMI safe */
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WARN_ON_ONCE(in_nmi());
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/* Only queue if not already pending */
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if (!irq_work_claim(work))
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return false;
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if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
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arch_send_call_function_single_ipi(cpu);
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#else /* #ifdef CONFIG_SMP */
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irq_work_queue(work);
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#endif /* #else #ifdef CONFIG_SMP */
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return true;
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/* If the work is "lazy", handle it from next tick if any */
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if (work->flags & IRQ_WORK_LAZY) {
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if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
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tick_nohz_tick_stopped())
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arch_irq_work_raise();
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} else {
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if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
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arch_irq_work_raise();
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}
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}
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/* Enqueue the irq work @work on the current CPU */
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@ -95,23 +79,48 @@ bool irq_work_queue(struct irq_work *work)
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/* Queue the entry and raise the IPI if needed. */
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preempt_disable();
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/* If the work is "lazy", handle it from next tick if any */
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if (work->flags & IRQ_WORK_LAZY) {
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if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
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tick_nohz_tick_stopped())
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arch_irq_work_raise();
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} else {
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if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
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arch_irq_work_raise();
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}
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__irq_work_queue_local(work);
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preempt_enable();
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return true;
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}
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EXPORT_SYMBOL_GPL(irq_work_queue);
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/*
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* Enqueue the irq_work @work on @cpu unless it's already pending
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* somewhere.
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*
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* Can be re-enqueued while the callback is still in progress.
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*/
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bool irq_work_queue_on(struct irq_work *work, int cpu)
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{
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#ifndef CONFIG_SMP
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return irq_work_queue(work);
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#else /* CONFIG_SMP: */
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/* All work should have been flushed before going offline */
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WARN_ON_ONCE(cpu_is_offline(cpu));
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/* Only queue if not already pending */
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if (!irq_work_claim(work))
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return false;
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preempt_disable();
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if (cpu != smp_processor_id()) {
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/* Arch remote IPI send/receive backend aren't NMI safe */
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WARN_ON_ONCE(in_nmi());
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if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
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arch_send_call_function_single_ipi(cpu);
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} else {
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__irq_work_queue_local(work);
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}
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preempt_enable();
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return true;
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#endif /* CONFIG_SMP */
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}
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bool irq_work_needs_cpu(void)
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{
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struct llist_head *raised, *lazy;
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