| Message ID | 20230504151100.v4.7.Id4133d3183e798122dc3b6205e7852601f289071@changeid (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | watchdog/hardlockup: Add the buddy hardlockup detector | expand |
On Fri May 5, 2023 at 8:13 AM AEST, Douglas Anderson wrote: > 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 I think the name change is a gratuitous. Especially since it's now static. watchdog_hardlockup_ is a pretty long prefix too, hardlockup_ should be enough? Seems okay otherwise though. Thanks, Nick > 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, move it to the same "#ifdef" block as our new > watchdog_hardlockup_check(), and rename it to make it obvious it's > just for hardlockup detectors. 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. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- > > Changes in v4: > - ("Move perf hardlockup checking/panic ...") new for v4. > > include/linux/nmi.h | 5 ++- > kernel/watchdog.c | 92 +++++++++++++++++++++++++++++++++--------- > kernel/watchdog_perf.c | 42 +------------------ > 3 files changed, 78 insertions(+), 61 deletions(-) > > diff --git a/include/linux/nmi.h b/include/linux/nmi.h > index 35d09d70f394..c6cb9bc5dc80 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 c705a18b26bf..2d319cdf64b9 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 watchdog_hardlockup_is_lockedup(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_interrupt_count(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 (watchdog_hardlockup_is_lockedup()) { > + 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_interrupt_count(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); > > @@ -359,7 +413,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) > return HRTIMER_NORESTART; > > /* kick the hardlockup detector */ > - watchdog_interrupt_count(); > + watchdog_hardlockup_interrupt_count(); > > /* kick the softlockup detector */ > if (completion_done(this_cpu_ptr(&softlockup_completion))) { > diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c > index c3d8ceb149da..5f3651b87ee7 100644 > --- a/kernel/watchdog_perf.c > +++ b/kernel/watchdog_perf.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, > 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 > - * 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) > -- > 2.40.1.521.gf1e218fcd8-goog
Hi, On Thu, May 4, 2023 at 7:58 PM Nicholas Piggin <npiggin@gmail.com> wrote: > > On Fri May 5, 2023 at 8:13 AM AEST, Douglas Anderson wrote: > > 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 > > I think the name change is a gratuitous. Especially since it's now > static. > > watchdog_hardlockup_ is a pretty long prefix too, hardlockup_ > should be enough? > > Seems okay otherwise though. I went back and forth on names far too much when constructing this patch series. Mostly I was trying to balance what looked good to me and what Petr suggested [1]. I'm not super picky about the names and I'm happy to change them all to a "hardlockup_" prefix. I'd love to hear Petr's opinion. [1] https://lore.kernel.org/r/ZFErmshcrcikrSU1@alley
diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 35d09d70f394..c6cb9bc5dc80 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 c705a18b26bf..2d319cdf64b9 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 watchdog_hardlockup_is_lockedup(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_interrupt_count(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 (watchdog_hardlockup_is_lockedup()) { + 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_interrupt_count(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); @@ -359,7 +413,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) return HRTIMER_NORESTART; /* kick the hardlockup detector */ - watchdog_interrupt_count(); + watchdog_hardlockup_interrupt_count(); /* kick the softlockup detector */ if (completion_done(this_cpu_ptr(&softlockup_completion))) { diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c index c3d8ceb149da..5f3651b87ee7 100644 --- a/kernel/watchdog_perf.c +++ b/kernel/watchdog_perf.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, 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 - * 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)
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, move it to the same "#ifdef" block as our new watchdog_hardlockup_check(), and rename it to make it obvious it's just for hardlockup detectors. 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. Signed-off-by: Douglas Anderson <dianders@chromium.org> --- Changes in v4: - ("Move perf hardlockup checking/panic ...") new for v4. include/linux/nmi.h | 5 ++- kernel/watchdog.c | 92 +++++++++++++++++++++++++++++++++--------- kernel/watchdog_perf.c | 42 +------------------ 3 files changed, 78 insertions(+), 61 deletions(-)