From: Douglas Anderson dianders@chromium.org
[ Upstream commit 4379e59fe5665cfda737e45b8bf2f05321ef049c ]
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.I843b0d1de3e096ba111a179f3adb1... Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes") Signed-off-by: Douglas 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: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/watchdog_hld.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 71381168dedef..f8e460b4a59d5 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -114,14 +114,14 @@ static void watchdog_overflow_callback(struct perf_event *event, /* Ensure the watchdog never gets throttled */ event->hw.interrupts = 0;
+ if (!watchdog_check_timestamp()) + return; + if (__this_cpu_read(watchdog_nmi_touch) == true) { __this_cpu_write(watchdog_nmi_touch, false); return; }
- if (!watchdog_check_timestamp()) - return; - /* check for a hardlockup * This is done by making sure our timer interrupt * is incrementing. The timer interrupt should have