Hi!
> Below is a patch from android kernel that detects a driver suspend
> lockup and captures dump in the kernel log. Please review and provide
> comments.
>
> Rather than hard-lock the kernel, dump the suspend thread stack and
> BUG() when a driver takes too long to suspend. The timeout is set to
> 12 seconds to be longer than the usbhid 10 second timeout.
>
> Exclude from the watchdog the time spent waiting for children that
> are resumed asynchronously and time every device, whether or not they
> resumed synchronously.
>
> Cc: Android Kernel Team <[email protected]>
> Cc: Colin Cross <[email protected]>
> Cc: Todd Poynor <[email protected]>
> Cc: San Mehat <[email protected]>
> Cc: Benoit Goby <[email protected]>
> Cc: John Stultz <[email protected]>
> Cc: Pavel Machek <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>
> Cc: Len Brown <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Original-author: San Mehat <[email protected]>
> Signed-off-by: Benoit Goby <[email protected]>
> [[email protected]: Changed printk(KERN_EMERG,...) to pr_emerg(...),
> tweaked commit message.]
> Signed-off-by: Zoran Markovic <[email protected]>
> ---
> drivers/base/power/main.c | 45
> +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 15beb50..eb70c0e 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -29,6 +29,8 @@
> #include <linux/async.h>
> #include <linux/suspend.h>
> #include <linux/cpuidle.h>
> +#include <linux/timer.h>
> +
> #include "../base.h"
> #include "power.h"
>
> @@ -54,6 +56,12 @@ struct suspend_stats suspend_stats;
> static DEFINE_MUTEX(dpm_list_mtx);
> static pm_message_t pm_transition;
>
> +static void dpm_drv_timeout(unsigned long data);
> +struct dpm_drv_wd_data {
> + struct device *dev;
> + struct task_struct *tsk;
> +};
> +
> static int async_error;
>
> /**
> @@ -663,6 +671,30 @@ static bool is_async(struct device *dev)
> }
>
> /**
> + * dpm_drv_timeout - Driver suspend / resume watchdog handler
> + * @data: struct device which timed out
> + *
> + * Called when a driver has timed out suspending or resuming.
> + * There's not much we can do here to recover so
> + * BUG() out for a crash-dump
> + *
> + */
> +static void dpm_drv_timeout(unsigned long data)
> +{
> + struct dpm_drv_wd_data *wd_data = (void *)data;
> + struct device *dev = wd_data->dev;
> + struct task_struct *tsk = wd_data->tsk;
> +
> + pr_emerg("**** DPM device timeout: %s (%s)\n", dev_name(dev),
> + (dev->driver ? dev->driver->name : "no driver"));
> +
> + pr_emerg("dpm suspend stack:\n");
> + show_stack(tsk, NULL);
> +
> + BUG();
> +}
So you:
dump stack of the suspend task
do BUG which
dumps stack of current task
kills current task
Current task may very well be idle task; in such case you kill the
machine. Sounds like you should be doing something else, like kill -9
instead of BUG()?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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