cd578abb24
On Mon, Feb 10, 2014 at 08:45:16AM -0800, Dave Hansen wrote:
> The reason I coded this up was that NMIs were firing off so fast that
> nothing else was getting a chance to run. With this patch, at least the
> printk() would come out and I'd have some idea what was going on.
It will start spewing to early_printk() (which is a lot nicer to use
from NMI context too) when it fails to queue the IRQ-work because its
already enqueued.
It does have the false-positive for when two CPUs trigger the warn
concurrently, but that should be rare and some extra clutter on the
early printk shouldn't be a problem.
Cc: hpa@zytor.com
Cc: tglx@linutronix.de
Cc: dzickus@redhat.com
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: mingo@kernel.org
Fixes: 6a02ad66b2 ("perf/x86: Push the duration-logging printk() to IRQ context")
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140211150116.GO27965@twins.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
46 lines
1.1 KiB
C
46 lines
1.1 KiB
C
#ifndef _LINUX_IRQ_WORK_H
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#define _LINUX_IRQ_WORK_H
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#include <linux/llist.h>
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/*
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* An entry can be in one of four states:
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*
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* free NULL, 0 -> {claimed} : free to be used
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* claimed NULL, 3 -> {pending} : claimed to be enqueued
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* pending next, 3 -> {busy} : queued, pending callback
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* busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
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*/
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#define IRQ_WORK_PENDING 1UL
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#define IRQ_WORK_BUSY 2UL
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#define IRQ_WORK_FLAGS 3UL
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#define IRQ_WORK_LAZY 4UL /* Doesn't want IPI, wait for tick */
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struct irq_work {
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unsigned long flags;
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struct llist_node llnode;
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void (*func)(struct irq_work *);
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};
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static inline
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void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *))
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{
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work->flags = 0;
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work->func = func;
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}
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#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { .func = (_f), }
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bool irq_work_queue(struct irq_work *work);
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void irq_work_run(void);
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void irq_work_sync(struct irq_work *work);
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#ifdef CONFIG_IRQ_WORK
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bool irq_work_needs_cpu(void);
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#else
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static inline bool irq_work_needs_cpu(void) { return false; }
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#endif
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#endif /* _LINUX_IRQ_WORK_H */
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