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Subject[PATCH v2] x86/nmi: Fix nmi_handle duration miscalculation
Date
In nmi_check_duration(), the 'whole_msecs' value get from
'action->max_duration' is wrong.

Fixes: 248ed51048c4 ("x86/nmi: Remove irq_work from the long duration NMI handler")
Signed-off-by: Libing Zhou <libing.zhou@nokia-sbell.com>
---
v2:
Change solution as peterz@infradead.org suggested.

arch/x86/kernel/nmi.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

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)
--
2.22.0
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