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x86, mce: always use separate work queue to run trigger 

Impact: Needed for bug fix in next patch

This relaxes the requirement that mce_notify_user has to run in process
context. Useful for future changes, but also leads to cleaner
behaviour now. Now instead mce_notify_user can be called directly
from interrupt (but not NMI) context.

The work queue only uses a single global work struct, which can be done safely
because it is always free to reuse before the trigger function is executed.
This way no events can be lost.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Andi Kleen 2009-02-12 13:39:28 +01:00 committed by H. Peter Anvin
parent 123aa76ec0
commit 9bd9840580
1 changed files with 18 additions and 7 deletions
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25
arch/x86/kernel/cpu/mcheck/mce_64.c
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@ -380,11 +380,17 @@ static void mcheck_timer(struct work_struct *work)
schedule_delayed_work(&mcheck_work, next_interval);
}
static void mce_do_trigger(struct work_struct *work)
{
call_usermodehelper(trigger, trigger_argv, NULL, UMH_NO_WAIT);
}
static DECLARE_WORK(mce_trigger_work, mce_do_trigger);
/*
* This is only called from process context. This is where we do
* anything we need to alert userspace about new MCEs. This is called
* directly from the poller and also from entry.S and idle, thanks to
* TIF_MCE_NOTIFY.
* Notify the user(s) about new machine check events.
* Can be called from interrupt context, but not from machine check/NMI
* context.
*/
int mce_notify_user(void)
{
@ -394,9 +400,14 @@ int mce_notify_user(void)
unsigned long now = jiffies;
wake_up_interruptible(&mce_wait);
if (trigger[0])
call_usermodehelper(trigger, trigger_argv, NULL,
UMH_NO_WAIT);
/*
* There is no risk of missing notifications because
* work_pending is always cleared before the function is
* executed.
*/
if (trigger[0] && !work_pending(&mce_trigger_work))
schedule_work(&mce_trigger_work);
if (time_after_eq(now, last_print + (check_interval*HZ))) {
last_print = now;