From: Douglas Anderson dianders@chromium.org
[ Upstream commit 81972551df9d168a8183b786ff4de06008469c2e ]
The perf hardlockup detector works by looking at interrupt counts and seeing if they change from run to run. The interrupt counts are managed by the common watchdog code via its watchdog_timer_fn().
Currently the API between the perf detector and the common code is a function: is_hardlockup(). When the hard lockup detector sees that function return true then it handles printing out debug info and inducing a panic if necessary.
Let's change the API a little bit in preparation for the buddy hardlockup detector. The buddy hardlockup detector wants to print nearly the same debug info and have nearly the same panic behavior. That means we want to move all that code to the common file. For now, the code in the common file will only be there if the perf hardlockup detector is enabled, but eventually it will be selected by a common config.
Right now, this _just_ moves the code from the perf detector file to the common file and changes the names. It doesn't make the changes that the buddy hardlockup detector will need and doesn't do any style cleanups. A future patch will do cleanup to make it more obvious what changed.
With the above, we no longer have any callers of is_hardlockup() outside of the "watchdog.c" file, so we can remove it from the header, make it static, and move it to the same "#ifdef" block as our new watchdog_hardlockup_check(). While doing this, it can be noted that even if no hardlockup detectors were configured the existing code used to still have the code for counting/checking "hrtimer_interrupts" even if the perf hardlockup detector wasn't configured. We didn't need to do that, so move all the "hrtimer_interrupts" counting to only be there if the perf hardlockup detector is configured as well.
This change is expected to be a no-op.
Link: https://lkml.kernel.org/r/20230519101840.v5.8.Id4133d3183e798122dc3b6205e785... Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Petr Mladek pmladek@suse.com 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: 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 Stable-dep-of: 9ec272c586b0 ("watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/nmi.h | 5 ++- kernel/watchdog.c | 93 +++++++++++++++++++++++++++++++++---------- kernel/watchdog_hld.c | 42 +------------------ 3 files changed, 78 insertions(+), 62 deletions(-)
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 454fe99c48747..97ba114bc21e7 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -15,7 +15,6 @@ void lockup_detector_init(void); void lockup_detector_soft_poweroff(void); void lockup_detector_cleanup(void); -bool is_hardlockup(void);
extern int watchdog_user_enabled; extern int nmi_watchdog_user_enabled; @@ -88,6 +87,10 @@ extern unsigned int hardlockup_panic; static inline void hardlockup_detector_disable(void) {} #endif
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF) +void watchdog_hardlockup_check(struct pt_regs *regs); +#endif + #if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR) # define NMI_WATCHDOG_SYSCTL_PERM 0644 #else diff --git a/kernel/watchdog.c b/kernel/watchdog.c index c705a18b26bf1..12ce37d76e7d2 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -85,6 +85,78 @@ __setup("nmi_watchdog=", hardlockup_panic_setup);
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF) + +static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); +static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); +static DEFINE_PER_CPU(bool, hard_watchdog_warn); +static unsigned long hardlockup_allcpu_dumped; + +static bool is_hardlockup(void) +{ + unsigned long hrint = __this_cpu_read(hrtimer_interrupts); + + if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) + return true; + + __this_cpu_write(hrtimer_interrupts_saved, hrint); + return false; +} + +static void watchdog_hardlockup_kick(void) +{ + __this_cpu_inc(hrtimer_interrupts); +} + +void watchdog_hardlockup_check(struct pt_regs *regs) +{ + /* check for a hardlockup + * This is done by making sure our timer interrupt + * is incrementing. The timer interrupt should have + * fired multiple times before we overflow'd. If it hasn't + * then this is a good indication the cpu is stuck + */ + if (is_hardlockup()) { + int this_cpu = smp_processor_id(); + + /* only print hardlockups once */ + if (__this_cpu_read(hard_watchdog_warn) == true) + return; + + pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n", + this_cpu); + print_modules(); + print_irqtrace_events(current); + if (regs) + show_regs(regs); + else + dump_stack(); + + /* + * Perform all-CPU dump only once to avoid multiple hardlockups + * generating interleaving traces + */ + if (sysctl_hardlockup_all_cpu_backtrace && + !test_and_set_bit(0, &hardlockup_allcpu_dumped)) + trigger_allbutself_cpu_backtrace(); + + if (hardlockup_panic) + nmi_panic(regs, "Hard LOCKUP"); + + __this_cpu_write(hard_watchdog_warn, true); + return; + } + + __this_cpu_write(hard_watchdog_warn, false); + return; +} + +#else /* CONFIG_HARDLOCKUP_DETECTOR_PERF */ + +static inline void watchdog_hardlockup_kick(void) { } + +#endif /* !CONFIG_HARDLOCKUP_DETECTOR_PERF */ + /* * These functions can be overridden if an architecture implements its * own hardlockup detector. @@ -176,8 +248,6 @@ static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); static DEFINE_PER_CPU(unsigned long, watchdog_report_ts); static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); static DEFINE_PER_CPU(bool, softlockup_touch_sync); -static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); -static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); static unsigned long soft_lockup_nmi_warn;
static int __init nowatchdog_setup(char *str) @@ -312,22 +382,6 @@ static int is_softlockup(unsigned long touch_ts, }
/* watchdog detector functions */ -bool is_hardlockup(void) -{ - unsigned long hrint = __this_cpu_read(hrtimer_interrupts); - - if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) - return true; - - __this_cpu_write(hrtimer_interrupts_saved, hrint); - return false; -} - -static void watchdog_interrupt_count(void) -{ - __this_cpu_inc(hrtimer_interrupts); -} - static DEFINE_PER_CPU(struct completion, softlockup_completion); static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
@@ -358,8 +412,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) if (!watchdog_enabled) return HRTIMER_NORESTART;
- /* kick the hardlockup detector */ - watchdog_interrupt_count(); + watchdog_hardlockup_kick();
/* kick the softlockup detector */ if (completion_done(this_cpu_ptr(&softlockup_completion))) { diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 1e8a49dc956e2..2e0e1e11227c5 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -20,13 +20,11 @@ #include <asm/irq_regs.h> #include <linux/perf_event.h>
-static DEFINE_PER_CPU(bool, hard_watchdog_warn); static DEFINE_PER_CPU(bool, watchdog_nmi_touch); static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); static DEFINE_PER_CPU(struct perf_event *, dead_event); static struct cpumask dead_events_mask;
-static unsigned long hardlockup_allcpu_dumped; static atomic_t watchdog_cpus = ATOMIC_INIT(0);
notrace void arch_touch_nmi_watchdog(void) @@ -122,45 +120,7 @@ static void watchdog_overflow_callback(struct perf_event *event, return; }
- /* check for a hardlockup - * This is done by making sure our timer interrupt - * is incrementing. The timer interrupt should have - * fired multiple times before we overflow'd. If it hasn't - * then this is a good indication the cpu is stuck - */ - if (is_hardlockup()) { - int this_cpu = smp_processor_id(); - - /* only print hardlockups once */ - if (__this_cpu_read(hard_watchdog_warn) == true) - return; - - pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n", - this_cpu); - print_modules(); - print_irqtrace_events(current); - if (regs) - show_regs(regs); - else - dump_stack(); - - /* - * Perform all-CPU dump only once to avoid multiple hardlockups - * generating interleaving traces - */ - if (sysctl_hardlockup_all_cpu_backtrace && - !test_and_set_bit(0, &hardlockup_allcpu_dumped)) - trigger_allbutself_cpu_backtrace(); - - if (hardlockup_panic) - nmi_panic(regs, "Hard LOCKUP"); - - __this_cpu_write(hard_watchdog_warn, true); - return; - } - - __this_cpu_write(hard_watchdog_warn, false); - return; + watchdog_hardlockup_check(regs); }
static int hardlockup_detector_event_create(void)