Messages in this thread Patch in this message | | | Date | Wed, 19 Aug 2020 10:06:45 +0200 | From | peterz@infradea ... | Subject | Re: [PATCH] x86/nmi: Fix nmi_handle duration miscalculation |
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On Mon, Aug 17, 2020 at 05:04:41PM +0800, Libing Zhou wrote: > In nmi_check_duration(), the 'whole_msecs' value should > get from 'duration' to reflect actual time duration, > but not 'action->max_duration'.
Fixes: 248ed51048c4 ("x86/nmi: Remove irq_work from the long duration NMI handler")
> Signed-off-by: Libing Zhou <libing.zhou@nokia-sbell.com> > --- > arch/x86/kernel/nmi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c > index 4fc9954a9560..c51ee659e520 100644 > --- a/arch/x86/kernel/nmi.c > +++ b/arch/x86/kernel/nmi.c > @@ -102,7 +102,7 @@ fs_initcall(nmi_warning_debugfs); > > static void nmi_check_duration(struct nmiaction *action, u64 duration) > { > - u64 whole_msecs = READ_ONCE(action->max_duration); > + u64 whole_msecs = duration; > int remainder_ns, decimal_msecs; > > if (duration < nmi_longest_ns || duration < action->max_duration)
The, IMO, saner solution is:
--- diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 4fc9954a9560..47381666d6a5 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -102,7 +102,6 @@ fs_initcall(nmi_warning_debugfs); static void nmi_check_duration(struct nmiaction *action, u64 duration) { - u64 whole_msecs = READ_ONCE(action->max_duration); int remainder_ns, decimal_msecs; if (duration < nmi_longest_ns || duration < action->max_duration) @@ -110,12 +109,12 @@ static void nmi_check_duration(struct nmiaction *action, u64 duration) action->max_duration = duration; - remainder_ns = do_div(whole_msecs, (1000 * 1000)); + remainder_ns = do_div(duration, (1000 * 1000)); decimal_msecs = remainder_ns / 1000; printk_ratelimited(KERN_INFO "INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n", - action->handler, whole_msecs, decimal_msecs); + action->handler, duration, decimal_msecs); } static int nmi_handle(unsigned int type, struct pt_regs *regs)
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