| Message ID | 1368221329-1841-3-git-send-email-zoran.markovic@linaro.org (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
On Fri, May 10, 2013 at 2:28 PM, Zoran Markovic <zoran.markovic@linaro.org> wrote: > Power management debug option to configure device suspend/resume watchdogs. > Available options are: > 1. Enable/disable the feature. > 2. Select triggered watchdog action between: > - system panic (default) > - dump stacktrace > - log event I don't see much point to logging the event but not printing the stack trace, you can just disable the feature if you don't want your logs cluttered, and this shouldn't fire very often. > 3. Select timeout value for the watchdog(s). > > Minor changes were made to watchdog code to accommodate this feature. > > Cc: Android Kernel Team <kernel-team@android.com> > Cc: Colin Cross <ccross@android.com> > Cc: Todd Poynor <toddpoynor@google.com> > Cc: San Mehat <san@google.com> > Cc: Benoit Goby <benoit@android.com> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Pavel Machek <pavel@ucw.cz> > Cc: Rafael J. Wysocki <rjw@sisk.pl> > Cc: Len Brown <len.brown@intel.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org> This whole patch is linked enough with the previous one that I suggest squashing them together, and expanding your comments above your signed off by to say you added configuration options. > --- > drivers/base/power/main.c | 37 ++++++++++++++++++++++++++-------- > kernel/power/Kconfig | 48 +++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 77 insertions(+), 8 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index a6a02c0..8e0bb33 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -392,6 +392,26 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, > return error; > } > > +#ifdef CONFIG_DPM_WD > +/** > + * dpm_wd_action - recovery from suspend/resume watchdog timeout > + * @wd: Watchdog. Must be allocated on the stack. > + */ > +#if defined(CONFIG_DPM_WD_ACTION_STACKTRACE) > +static inline void dpm_wd_action(struct dpm_watchdog *wd) > +{ > + show_stack(wd->tsk, NULL); > +} > +#elif defined(CONFIG_DPM_WD_ACTION_PANIC) > +static inline void dpm_wd_action(struct dpm_watchdog *wd) > +{ > + panic("%s: unrecoverable failure\n", dev_name(wd->dev)); The panic here is not very useful, it's going to print the stack of the task that was running when the timer fired which is likely to be the idle task if the suspend task is deadlocked. This should call show_stack and panic. If you take out the log action, then all this can stay inline with the handler and be: dev_emerg(wd->dev, "**** DPM device timeout ****\n"); show_stack(wd->tsk, NULL); #ifdef CONFIG_DPM_WD_ACTION_PANIC panic("%s: unrecoverable failure\n", dev_name(wd->dev)); #endif Also, and this is a problem with the existing patch and not your modifications, the format devname: error in the log is usually printed by the device driver, which may cause confusion for someone who sees this error and tries to grep for it in the mentioned driver. Maybe a better format for the pr_emerg and the panic would be: PM: **** DPM device timeout suspending devname **** Ideally the message would specify if the error happened while suspending or resuming. > +} > +#else /* CONFIG_DPM_WD_ACTION_LOG */ > +/* event already logged in dpm_wd_handler() */ > +#define dpm_wd_action(x) > +#endif > + > /** > * dpm_wd_handler - Driver suspend / resume watchdog handler. > * > @@ -402,13 +422,9 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, > static void dpm_wd_handler(unsigned long data) > { > struct dpm_watchdog *wd = (void *)data; > - struct device *dev = wd->dev; > - struct task_struct *tsk = wd->tsk; > - > - dev_emerg(dev, "**** DPM device timeout ****\n"); > - show_stack(tsk, NULL); > > - BUG(); > + dev_emerg(wd->dev, "**** DPM device timeout ****\n"); > + dpm_wd_action(wd); > } > > /** > @@ -424,14 +440,15 @@ static void dpm_wd_set(struct dpm_watchdog *wd, struct device *dev) > wd->tsk = get_current(); > > init_timer_on_stack(timer); > - timer->expires = jiffies + HZ * 12; > + /* use same timeout value for both suspend and resume */ > + timer->expires = jiffies + HZ * CONFIG_DPM_WD_TIMEOUT; > timer->function = dpm_wd_handler; > timer->data = (unsigned long)wd; > add_timer(timer); > } > > /** > - * dpm_wd_clear - Disable pm watchdog. > + * dpm_wd_clear - Disable suspend/resume watchdog. > * @wd: Watchdog to disable. > */ > static void dpm_wd_clear(struct dpm_watchdog *wd) > @@ -441,6 +458,10 @@ static void dpm_wd_clear(struct dpm_watchdog *wd) > del_timer_sync(timer); > destroy_timer_on_stack(timer); > } > +#else > +#define dpm_wd_set(x, y) > +#define dpm_wd_clear(x) > +#endif > > /*------------------------- Resume routines -------------------------*/ > > diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig > index edc8bdd..339caa1 100644 > --- a/kernel/power/Kconfig > +++ b/kernel/power/Kconfig > @@ -179,6 +179,54 @@ config PM_SLEEP_DEBUG > def_bool y > depends on PM_DEBUG && PM_SLEEP > > +config DPM_WD > + bool "Device suspend/resume watchdog" > + depends on PM_DEBUG > + ---help--- > + Sets up a watchdog timer to capture drivers that are > + locked up attempting to suspend/resume a device. > + A detected lockup causes a configurable watchdog action, > + such as logging the event, dumping the stack trace or > + kernel panic. > + > +choice > + prompt "Watchdog recovery action" > + default DPM_WD_ACTION_PANIC > + depends on DPM_WD > + ---help--- > + Select recovery action triggered by suspend/resume watchdog. > + > +config DPM_WD_ACTION_PANIC > + bool "System panic" > + ---help--- > + When selected, a lockup during device's suspend or > + resume would cause a system panic. This would immediately > + capture user's attention. Panic message can be observed in > + subsequent boot session using pstore. > + > +config DPM_WD_ACTION_STACKTRACE > + bool "Dump stack" > + ---help--- > + When selected, a lockup during device's suspend or > + resume would cause the caller's stack to be > + captured in the system log. The stack trace shows > + which driver call caused a lockup. > + > +config DPM_WD_ACTION_LOG > + bool "Log event" > + ---help--- > + When selected, a lockup during device's suspend or > + resume would cause the watchdog timeout event to be > + logged in the system log. > + > +endchoice > + > +config DPM_WD_TIMEOUT > + int "Watchdog timeout in seconds" > + range 1 120 > + default 12 > + depends on DPM_WD > + > config PM_TRACE > bool > help > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi! > Power management debug option to configure device suspend/resume watchdogs. > Available options are: > 1. Enable/disable the feature. > 2. Select triggered watchdog action between: > - system panic (default) > - dump stacktrace > - log event > 3. Select timeout value for the watchdog(s). People disliked the previous behaviour, so you add 10 config options... with different behaviours. Also 1 second timeout is not acceptable for endusers (will break the system), so it should not be offered. In fact, remove that option, too. People doing that kind of debugging can modify the sources, right? (Maybe it would make sense to do same action regular watchdog does, but...) That's not the way to go. If "panic" is right behaviour, just go with panic. > @@ -402,13 +422,9 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, > static void dpm_wd_handler(unsigned long data) > { > struct dpm_watchdog *wd = (void *)data; > - struct device *dev = wd->dev; > - struct task_struct *tsk = wd->tsk; > - > - dev_emerg(dev, "**** DPM device timeout ****\n"); > - show_stack(tsk, NULL); > > - BUG(); > + dev_emerg(wd->dev, "**** DPM device timeout ****\n"); > + dpm_wd_action(wd); > } > > /** And merge this to previous patch. Introducing the code then redoing it in next patch does not help review. Pavel
On Sat, May 11, 2013 at 2:28 AM, Pavel Machek <pavel@ucw.cz> wrote: > Hi! > >> Power management debug option to configure device suspend/resume watchdogs. >> Available options are: >> 1. Enable/disable the feature. >> 2. Select triggered watchdog action between: >> - system panic (default) >> - dump stacktrace >> - log event >> 3. Select timeout value for the watchdog(s). > > People disliked the previous behaviour, so you add 10 config > options... with different behaviours. Also 1 second timeout is not > acceptable for endusers (will break the system), so it should not be > offered. In fact, remove that option, too. People doing that kind of > debugging can modify the sources, right? Greg KH asked for more configurable options. I agree this may be a little too far (I would replace the action choice with a simple "panic on timeout?"), but its better than it was before. Also, a 1 second timeout is perfectly reasonable, especially if you configure it to dump a stack trace but not panic. Mobile devices normally finish suspending within a few hundred ms. > (Maybe it would make sense to do same action regular watchdog does, > but...) > > That's not the way to go. If "panic" is right behaviour, just go with > panic. I can see uses for both panic and stack trace. If you have a driver that takes too long, but eventually suspends, then a panic is unnecessary and a stack trace that you can see in the logs is better, especially for a short timeout. >> @@ -402,13 +422,9 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, >> static void dpm_wd_handler(unsigned long data) >> { >> struct dpm_watchdog *wd = (void *)data; >> - struct device *dev = wd->dev; >> - struct task_struct *tsk = wd->tsk; >> - >> - dev_emerg(dev, "**** DPM device timeout ****\n"); >> - show_stack(tsk, NULL); >> >> - BUG(); >> + dev_emerg(wd->dev, "**** DPM device timeout ****\n"); >> + dpm_wd_action(wd); >> } >> >> /** > > And merge this to previous patch. Introducing the code then redoing it > in next patch does not help review. > > Pavel > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi! > >> Power management debug option to configure device suspend/resume watchdogs. > >> Available options are: > >> 1. Enable/disable the feature. > >> 2. Select triggered watchdog action between: > >> - system panic (default) > >> - dump stacktrace > >> - log event > >> 3. Select timeout value for the watchdog(s). > > > > People disliked the previous behaviour, so you add 10 config > > options... with different behaviours. Also 1 second timeout is not > > acceptable for endusers (will break the system), so it should not be > > offered. In fact, remove that option, too. People doing that kind of > > debugging can modify the sources, right? > > Greg KH asked for more configurable options. I agree this may be a > little too far (I would replace the action choice with a simple "panic > on timeout?"), but its better than it was before. Also, a 1 second > timeout is perfectly reasonable, especially if you configure it to > dump a stack trace but not panic. Mobile devices normally finish > suspending within a few hundred ms. For stack dump, yes that's ok. Maybe it ends up less ugly if it will be runtime-configurable?
On 05/10/2013 11:23 PM, Colin Cross wrote: > On Fri, May 10, 2013 at 2:28 PM, Zoran Markovic > <zoran.markovic@linaro.org> wrote: >> +#ifdef CONFIG_DPM_WD >> +/** >> + * dpm_wd_action - recovery from suspend/resume watchdog timeout >> + * @wd: Watchdog. Must be allocated on the stack. >> + */ >> +#if defined(CONFIG_DPM_WD_ACTION_STACKTRACE) >> +static inline void dpm_wd_action(struct dpm_watchdog *wd) >> +{ >> + show_stack(wd->tsk, NULL); >> +} >> +#elif defined(CONFIG_DPM_WD_ACTION_PANIC) >> +static inline void dpm_wd_action(struct dpm_watchdog *wd) >> +{ >> + panic("%s: unrecoverable failure\n", dev_name(wd->dev)); > The panic here is not very useful, it's going to print the stack of > the task that was running when the timer fired which is likely to be > the idle task if the suspend task is deadlocked. This should call > show_stack and panic. If you take out the log action, then all this > can stay inline with the handler and be: > > dev_emerg(wd->dev, "**** DPM device timeout ****\n"); > show_stack(wd->tsk, NULL); > #ifdef CONFIG_DPM_WD_ACTION_PANIC > panic("%s: unrecoverable failure\n", dev_name(wd->dev)); > #endif #ifdefs in functions are usually to be avoided. Thus why I suggested he use the config dependent dpm_wd_action() function to handle this. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index a6a02c0..8e0bb33 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -392,6 +392,26 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, return error; } +#ifdef CONFIG_DPM_WD +/** + * dpm_wd_action - recovery from suspend/resume watchdog timeout + * @wd: Watchdog. Must be allocated on the stack. + */ +#if defined(CONFIG_DPM_WD_ACTION_STACKTRACE) +static inline void dpm_wd_action(struct dpm_watchdog *wd) +{ + show_stack(wd->tsk, NULL); +} +#elif defined(CONFIG_DPM_WD_ACTION_PANIC) +static inline void dpm_wd_action(struct dpm_watchdog *wd) +{ + panic("%s: unrecoverable failure\n", dev_name(wd->dev)); +} +#else /* CONFIG_DPM_WD_ACTION_LOG */ +/* event already logged in dpm_wd_handler() */ +#define dpm_wd_action(x) +#endif + /** * dpm_wd_handler - Driver suspend / resume watchdog handler. * @@ -402,13 +422,9 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev, static void dpm_wd_handler(unsigned long data) { struct dpm_watchdog *wd = (void *)data; - struct device *dev = wd->dev; - struct task_struct *tsk = wd->tsk; - - dev_emerg(dev, "**** DPM device timeout ****\n"); - show_stack(tsk, NULL); - BUG(); + dev_emerg(wd->dev, "**** DPM device timeout ****\n"); + dpm_wd_action(wd); } /** @@ -424,14 +440,15 @@ static void dpm_wd_set(struct dpm_watchdog *wd, struct device *dev) wd->tsk = get_current(); init_timer_on_stack(timer); - timer->expires = jiffies + HZ * 12; + /* use same timeout value for both suspend and resume */ + timer->expires = jiffies + HZ * CONFIG_DPM_WD_TIMEOUT; timer->function = dpm_wd_handler; timer->data = (unsigned long)wd; add_timer(timer); } /** - * dpm_wd_clear - Disable pm watchdog. + * dpm_wd_clear - Disable suspend/resume watchdog. * @wd: Watchdog to disable. */ static void dpm_wd_clear(struct dpm_watchdog *wd) @@ -441,6 +458,10 @@ static void dpm_wd_clear(struct dpm_watchdog *wd) del_timer_sync(timer); destroy_timer_on_stack(timer); } +#else +#define dpm_wd_set(x, y) +#define dpm_wd_clear(x) +#endif /*------------------------- Resume routines -------------------------*/ diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index edc8bdd..339caa1 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -179,6 +179,54 @@ config PM_SLEEP_DEBUG def_bool y depends on PM_DEBUG && PM_SLEEP +config DPM_WD + bool "Device suspend/resume watchdog" + depends on PM_DEBUG + ---help--- + Sets up a watchdog timer to capture drivers that are + locked up attempting to suspend/resume a device. + A detected lockup causes a configurable watchdog action, + such as logging the event, dumping the stack trace or + kernel panic. + +choice + prompt "Watchdog recovery action" + default DPM_WD_ACTION_PANIC + depends on DPM_WD + ---help--- + Select recovery action triggered by suspend/resume watchdog. + +config DPM_WD_ACTION_PANIC + bool "System panic" + ---help--- + When selected, a lockup during device's suspend or + resume would cause a system panic. This would immediately + capture user's attention. Panic message can be observed in + subsequent boot session using pstore. + +config DPM_WD_ACTION_STACKTRACE + bool "Dump stack" + ---help--- + When selected, a lockup during device's suspend or + resume would cause the caller's stack to be + captured in the system log. The stack trace shows + which driver call caused a lockup. + +config DPM_WD_ACTION_LOG + bool "Log event" + ---help--- + When selected, a lockup during device's suspend or + resume would cause the watchdog timeout event to be + logged in the system log. + +endchoice + +config DPM_WD_TIMEOUT + int "Watchdog timeout in seconds" + range 1 120 + default 12 + depends on DPM_WD + config PM_TRACE bool help
Power management debug option to configure device suspend/resume watchdogs. Available options are: 1. Enable/disable the feature. 2. Select triggered watchdog action between: - system panic (default) - dump stacktrace - log event 3. Select timeout value for the watchdog(s). Minor changes were made to watchdog code to accommodate this feature. Cc: Android Kernel Team <kernel-team@android.com> Cc: Colin Cross <ccross@android.com> Cc: Todd Poynor <toddpoynor@google.com> Cc: San Mehat <san@google.com> Cc: Benoit Goby <benoit@android.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Len Brown <len.brown@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org> --- drivers/base/power/main.c | 37 ++++++++++++++++++++++++++-------- kernel/power/Kconfig | 48 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+), 8 deletions(-)