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    SubjectRe: [PATCH v5 02/18] watchdog/perf: More properly prevent false positives with turbo modes
    On Fri 2023-05-19 10:18:26, Douglas Anderson wrote:
    > Currently, in the watchdog_overflow_callback() we first check to see
    > if the watchdog had been touched and _then_ we handle the workaround
    > for turbo mode. This order should be reversed.
    >
    > Specifically, "touching" the hardlockup detector's watchdog should
    > avoid lockups being detected for one period that should be roughly the
    > same regardless of whether we're running turbo or not. That means that
    > we should do the extra accounting for turbo _before_ we look at (and
    > clear) the global indicating that we've been touched.

    The ideal solution would be to reset the turbo-mode-related
    variables when the watchdog is touched. And keep checking
    watchdog_nmi_touch first.

    But this ordering change should be good enough. It causes that
    we always check watchdog_nmi_touch when the turbo-more-related
    variables are already reset.

    > NOTE: this fix is made based on code inspection. I am not aware of any
    > reports where the old code would have generated false positives. That
    > being said, this order seems more correct and also makes it easier
    > down the line to share code with the "buddy" hardlockup detector.
    >
    > Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes")
    > Signed-off-by: Douglas Anderson <dianders@chromium.org>

    Reviewed-by: Petr Mladek <pmladek@suse.com>

    Best Regards,
    Petr

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