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authorPeter Zijlstra <peterz@infradead.org>2014-02-11 16:01:16 +0100
committerThomas Gleixner <tglx@linutronix.de>2014-02-21 21:49:07 +0100
commitcd578abb24aa67ce468c427d3356c08ea32cf768 (patch)
tree974a97cebfc368e8bee9c1beccbbd9bda00d89ef /kernel/irq_work.c
parent90ed5b0fa5eb96e1cbb34aebf6a9ed96ee1587ec (diff)
downloadlinux-sh-cd578abb24aa67ce468c427d3356c08ea32cf768.tar.gz
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 <dave.hansen@linux.intel.com> Cc: mingo@kernel.org Fixes: 6a02ad66b2c4 ("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>
Diffstat (limited to 'kernel/irq_work.c')
-rw-r--r--kernel/irq_work.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 55fcce6065cf..a82170e2fa78 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -61,11 +61,11 @@ void __weak arch_irq_work_raise(void)
*
* Can be re-enqueued while the callback is still in progress.
*/
-void irq_work_queue(struct irq_work *work)
+bool irq_work_queue(struct irq_work *work)
{
/* Only queue if not already pending */
if (!irq_work_claim(work))
- return;
+ return false;
/* Queue the entry and raise the IPI if needed. */
preempt_disable();
@@ -83,6 +83,8 @@ void irq_work_queue(struct irq_work *work)
}
preempt_enable();
+
+ return true;
}
EXPORT_SYMBOL_GPL(irq_work_queue);