Grumble, somehow these emails got lost in the crowd.

On Fri, 2013-04-26 at 10:24 +0200, Sebastian Andrzej Siewior wrote:

* Steven Rostedt | 2013-04-11 14:33:34 [-0400]:

quoted

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index e8d8ad0..060e473 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c

@@ -1308,6 +1309,61 @@ static void mce_do_trigger(struct work_struct *work)

static DECLARE_WORK(mce_trigger_work, mce_do_trigger);

+static void __mce_notify_work(void)
+{
+	/* Not more than two messages every minute */
+	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
+
+	/* wake processes polling /dev/mcelog */
+	wake_up_interruptible(&mce_chrdev_wait);
+
+	/*
+	 * There is no risk of missing notifications because
+	 * work_pending is always cleared before the function is
+	 * executed.
+	 */
+	if (mce_helper[0] && !work_pending(&mce_trigger_work))
+		schedule_work(&mce_trigger_work);

Why is here this work_pending() check? You can't enqueue a work item
twice.

Yep, that doesn't look needed. Looking at the current code we have this
commit:

commit 4d899be584d4b4c5d6b49d655176b25cebf6ff1a
Author: Tejun Heo [off-list ref]
Date:   Fri Dec 21 17:57:05 2012 -0800

    x86/mce: don't use [delayed_]work_pending()
    
    There's no need to test whether a (delayed) work item in pending
    before queueing, flushing or cancelling it.  Most uses are unnecessary
    and quite a few of them are buggy.
    
    Remove unnecessary pending tests from x86/mce.  Only compile tested.
    
    v2: Local var work removed from mce_schedule_work() as suggested by
        Borislav.


-- Steve