From cd578abb24aa67ce468c427d3356c08ea32cf768 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 11 Feb 2014 16:01:16 +0100 Subject: perf/x86: Warn to early_printk() in case irq_work is too slow 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 Cc: mingo@kernel.org Fixes: 6a02ad66b2c4 ("perf/x86: Push the duration-logging printk() to IRQ context") Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140211150116.GO27965@twins.programming.kicks-ass.net Signed-off-by: Thomas Gleixner --- include/linux/irq_work.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/irq_work.h') diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index add13c8624b7..19ae05d4b8ec 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -32,7 +32,7 @@ void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *)) #define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { .func = (_f), } -void irq_work_queue(struct irq_work *work); +bool irq_work_queue(struct irq_work *work); void irq_work_run(void); void irq_work_sync(struct irq_work *work); -- cgit