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Commit 9bd98405 authored by Andi Kleen's avatar Andi Kleen Committed by H. Peter Anvin
Browse files

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: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 123aa76e

arch/x86/kernel/cpu/mcheck/mce_64.c

+18 −7
Original line number Diff line number Diff line
@@ -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;