• Douglas Anderson's avatar
    watchdog/perf: more properly prevent false positives with turbo modes · 4379e59f
    Douglas Anderson authored
    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.
    
    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.
    
    Link: https://lkml.kernel.org/r/20230519101840.v5.2.I843b0d1de3e096ba111a179f3adb16d576bef5c7@changeid
    Fixes: 7edaeb68 ("kernel/watchdog: Prevent false positives with turbo modes")
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Chen-Yu Tsai <wens@csie.org>
    Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
    Cc: Colin Cross <ccross@android.com>
    Cc: Daniel Thompson <daniel.thompson@linaro.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Guenter Roeck <groeck@chromium.org>
    Cc: Ian Rogers <irogers@google.com>
    Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
    Cc: Marc Zyngier <maz@kernel.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
    Cc: Matthias Kaehlcke <mka@chromium.org>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Nicholas Piggin <npiggin@gmail.com>
    Cc: Petr Mladek <pmladek@suse.com>
    Cc: Pingfan Liu <kernelfans@gmail.com>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
    Cc: Ricardo Neri <ricardo.neri@intel.com>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Stephen Boyd <swboyd@chromium.org>
    Cc: Sumit Garg <sumit.garg@linaro.org>
    Cc: Tzung-Bi Shih <tzungbi@chromium.org>
    Cc: Will Deacon <will@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    4379e59f
watchdog_hld.c 7.68 KB