linux-kernel - [PATCH 7/9] irq_work: Warn if there's still work on cpu

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Date:	Sun, 18 Nov 2012 02:04:50 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 7/9] irq_work: Warn if there's still work on cpu_down

From: Steven Rostedt <rostedt@...dmis.org>

If we are in nohz and there's still irq_work to be done when the idle
task is about to go offline, give a nasty warning. Everything should
have been flushed from the CPU_DYING notifier already. Further attempts
to enqueue an irq_work are buggy because irqs are disabled by
__cpu_disable(). The best we can do is to report the issue to the user.

Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/irq_work.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 4ed1749..480f747 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -109,6 +109,9 @@ bool irq_work_needs_cpu(void)
 	if (llist_empty(this_list))
 		return false;
 
+	/* All work should have been flushed before going offline */
+	WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
+
 	return true;
 }
 
-- 
1.7.5.4

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