irq_work: Warn if there's still work on cpu_down

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@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 4ed17490f6299cf67ea40e41ee03b7351dad4163..480f74715ba97b0d4885baf4892e0abcbe803eef 100644 (file)
--- 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;
 }