Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [3/10] x86: MCE: Always use separate work queue to run trigger | Date | Thu, 12 Feb 2009 13:37:22 +0100 (CET) |
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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>
--- arch/x86/kernel/cpu/mcheck/mce_64.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-)
Index: linux/arch/x86/kernel/cpu/mcheck/mce_64.c =================================================================== --- linux.orig/arch/x86/kernel/cpu/mcheck/mce_64.c 2009-02-12 11:30:51.000000000 +0100 +++ linux/arch/x86/kernel/cpu/mcheck/mce_64.c 2009-02-12 12:10:21.000000000 +0100 @@ -380,11 +380,17 @@ 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 @@ 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;
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