On Wednesday, May 06, 2015 10:47:24 PM Fu, Zhonghui wrote:
> Some system-hang occur only when multiple device PM methods
> are running asynchronously. So should cancel the synchronization
> of pm-trace, and make it suitable for asynchronous PM environment.
> 
> Signed-off-by: Zhonghui Fu <zhonghui...@linux.intel.com>
> ---
>  drivers/base/power/main.c |   53 +++++++++++++++++++++-----------------------
>  include/linux/pm-trace.h  |   24 ++++++++++++--------
>  kernel/power/main.c       |    2 +
>  3 files changed, 41 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 3d874ec..40daf48 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -476,9 +476,6 @@ static int device_resume_noirq(struct device *dev, 
> pm_message_t state, bool asyn
>       char *info = NULL;
>       int error = 0;
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_RESUME(0);
> -
>       if (dev->power.syscore || dev->power.direct_complete)
>               goto Out;
>  
> @@ -506,19 +503,21 @@ static int device_resume_noirq(struct device *dev, 
> pm_message_t state, bool asyn
>               callback = pm_noirq_op(dev->driver->pm, state);
>       }
>  
> +     TRACE_DEVICE_START(dev);
> +     TRACE_RESUME(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>       dev->power.is_noirq_suspended = false;
>  
> +     TRACE_DEVICE_END();
>   Out:
>       complete_all(&dev->power.completion);
> -     TRACE_RESUME(error);
>       return error;
>  }
>  
>  static bool is_async(struct device *dev)
>  {
> -     return dev->power.async_suspend && pm_async_enabled
> -             && !pm_trace_is_enabled();
> +     return dev->power.async_suspend && pm_async_enabled;
>  }
>  
>  static void async_resume_noirq(void *data, async_cookie_t cookie)
> @@ -605,9 +604,6 @@ static int device_resume_early(struct device *dev, 
> pm_message_t state, bool asyn
>       char *info = NULL;
>       int error = 0;
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_RESUME(0);
> -
>       if (dev->power.syscore || dev->power.direct_complete)
>               goto Out;
>  
> @@ -635,12 +631,14 @@ static int device_resume_early(struct device *dev, 
> pm_message_t state, bool asyn
>               callback = pm_late_early_op(dev->driver->pm, state);
>       }
>  
> +     TRACE_DEVICE_START(dev);
> +     TRACE_RESUME(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>       dev->power.is_late_suspended = false;
>  
> +     TRACE_DEVICE_END();
>   Out:
> -     TRACE_RESUME(error);
> -
>       pm_runtime_enable(dev);
>       complete_all(&dev->power.completion);
>       return error;
> @@ -734,9 +732,6 @@ static int device_resume(struct device *dev, pm_message_t 
> state, bool async)
>       int error = 0;
>       DECLARE_DPM_WATCHDOG_ON_STACK(wd);
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_RESUME(0);
> -
>       if (dev->power.syscore)
>               goto Complete;
>  
> @@ -801,9 +796,13 @@ static int device_resume(struct device *dev, 
> pm_message_t state, bool async)
>       }
>  
>   End:
> +     TRACE_DEVICE_START(dev);
> +     TRACE_RESUME(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>       dev->power.is_suspended = false;
>  
> +     TRACE_DEVICE_END();
>   Unlock:
>       device_unlock(dev);
>       dpm_watchdog_clear(&wd);
> @@ -811,8 +810,6 @@ static int device_resume(struct device *dev, pm_message_t 
> state, bool async)
>   Complete:
>       complete_all(&dev->power.completion);
>  
> -     TRACE_RESUME(error);
> -
>       return error;
>  }
>  
> @@ -1017,9 +1014,6 @@ static int __device_suspend_noirq(struct device *dev, 
> pm_message_t state, bool a
>       char *info = NULL;
>       int error = 0;
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_SUSPEND(0);
> -
>       if (async_error)
>               goto Complete;
>  
> @@ -1052,15 +1046,18 @@ static int __device_suspend_noirq(struct device *dev, 
> pm_message_t state, bool a
>               callback = pm_noirq_op(dev->driver->pm, state);
>       }
>  
> +     TRACE_DEVICE_START(dev);
> +     TRACE_SUSPEND(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>       if (!error)
>               dev->power.is_noirq_suspended = true;
>       else
>               async_error = error;
>  
> +     TRACE_DEVICE_END();
>  Complete:
>       complete_all(&dev->power.completion);
> -     TRACE_SUSPEND(error);
>       return error;
>  }
>  
> @@ -1161,9 +1158,6 @@ static int __device_suspend_late(struct device *dev, 
> pm_message_t state, bool as
>       char *info = NULL;
>       int error = 0;
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_SUSPEND(0);
> -
>       __pm_runtime_disable(dev, false);
>  
>       if (async_error)
> @@ -1198,14 +1192,17 @@ static int __device_suspend_late(struct device *dev, 
> pm_message_t state, bool as
>               callback = pm_late_early_op(dev->driver->pm, state);
>       }
>  
> +     TRACE_DEVICE_START(dev);
> +     TRACE_SUSPEND(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>       if (!error)
>               dev->power.is_late_suspended = true;
>       else
>               async_error = error;
>  
> +     TRACE_DEVICE_END();
>  Complete:
> -     TRACE_SUSPEND(error);
>       complete_all(&dev->power.completion);
>       return error;
>  }
> @@ -1346,9 +1343,6 @@ static int __device_suspend(struct device *dev, 
> pm_message_t state, bool async)
>       int error = 0;
>       DECLARE_DPM_WATCHDOG_ON_STACK(wd);
>  
> -     TRACE_DEVICE(dev);
> -     TRACE_SUSPEND(0);
> -
>       dpm_wait_for_children(dev, async);
>  
>       if (async_error)
> @@ -1428,8 +1422,12 @@ static int __device_suspend(struct device *dev, 
> pm_message_t state, bool async)
>               callback = pm_op(dev->driver->pm, state);
>       }
>  
> +     TRACE_DEVICE_START(dev);
> +     TRACE_SUSPEND(0);
> +
>       error = dpm_run_callback(callback, dev, state, info);
>  
> +     TRACE_DEVICE_END();
>   End:
>       if (!error) {
>               struct device *parent = dev->parent;
> @@ -1455,7 +1453,6 @@ static int __device_suspend(struct device *dev, 
> pm_message_t state, bool async)
>       if (error)
>               async_error = error;
>  
> -     TRACE_SUSPEND(error);
>       return error;
>  }
>  
> diff --git a/include/linux/pm-trace.h b/include/linux/pm-trace.h
> index ecbde7a..aa480b1 100644
> --- a/include/linux/pm-trace.h
> +++ b/include/linux/pm-trace.h
> @@ -6,29 +6,33 @@
>  #include <linux/types.h>
>  
>  extern int pm_trace_enabled;
> -
> -static inline int pm_trace_is_enabled(void)
> -{
> -       return pm_trace_enabled;
> -}
> +extern struct mutex pt_mutex;
>  
>  struct device;
>  extern void set_trace_device(struct device *);
>  extern void generate_pm_trace(const void *tracedata, unsigned int user);
>  extern int show_trace_dev_match(char *buf, size_t size);
>  
> -#define TRACE_DEVICE(dev) do { \
> +#define TRACE_DEVICE_START(dev) do { \
>       if (pm_trace_enabled) \
> +             mutex_lock(&pt_mutex); \
>               set_trace_device(dev); \
>       } while(0)
>  
> +#define TRACE_DEVICE_END() \
> +do { \
> +     if (pm_trace_enabled) { \
> +             mutex_unlock(&pt_mutex); \
> +     } \
> +} while (0)
> +

Won't this serialize the whole thing again?

>  #else
>  
> -static inline int pm_trace_is_enabled(void) { return 0; }
> +#define TRACE_DEVICE_START(dev) do { } while (0)
> +#define TRACE_DEVICE_END() do { } while (0)
>  
> -#define TRACE_DEVICE(dev) do { } while (0)
> -#define TRACE_RESUME(dev) do { } while (0)
> -#define TRACE_SUSPEND(dev) do { } while (0)
> +#define TRACE_RESUME(user) do { } while (0)
> +#define TRACE_SUSPEND(user) do { } while (0)
>  
>  #endif
>  
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 86e8157..ffd5145 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -515,6 +515,7 @@ power_attr(wake_unlock);
>  
>  #ifdef CONFIG_PM_TRACE
>  int pm_trace_enabled;
> +struct mutex pt_mutex;
>  
>  static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute 
> *attr,
>                            char *buf)
> @@ -533,6 +534,7 @@ pm_trace_store(struct kobject *kobj, struct 
> kobj_attribute *attr,
>               if (pm_trace_enabled) {
>                       pr_warn("PM: Enabling pm_trace changes system date and 
> time during resume.\n"
>                               "PM: Correct system time has to be restored 
> manually after resume.\n");
> +                     mutex_init(&pt_mutex);
>               }
>               return n;
>       }
> -- 1.7.1
> 
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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