linux-kernel - Re: [RESEND PATCH 1/2] PM / sleep: print function name of callbacks

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Date:   Wed, 19 Oct 2016 17:52:43 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Brian Norris <briannorris@...omium.org>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Doug Anderson <dianders@...omium.org>,
        Brian Norris <computersforpeace@...il.com>,
        Jeffy Chen <jeffy.chen@...k-chips.com>,
        linux-pm@...r.kernel.org, Chuansheng Liu <chuansheng.liu@...el.com>
Subject: Re: [RESEND PATCH 1/2] PM / sleep: print function name of callbacks

On Wed, Oct 19, 2016 at 05:26:09PM -0700, Brian Norris wrote:
> From: Douglas Anderson <dianders@...omium.org>
> 
> The printouts writen to the logs by suspend can be a bit opaque: it can
> be hard to track them down to the actual function called.  You might
> see:
> 
>   calling  rfkill1+ @ 19473, parent: phy0
>   call rfkill1+ returned 0 after 1 usecs
>   calling  phy0+ @ 19473, parent: mmc2:0001:1
>   call phy0+ returned 0 after 19 usecs
> 
> It's a bit hard to know what's actually happening.  Instead, it's nice
> to see:
> 
>   calling  rfkill1+ @ 15793, parent: phy0, cb: rfkill_suspend
>   call rfkill1+ returned 0 after 1 usecs
>   calling  phy0+ @ 15793, parent: mmc2:0001:1, cb: wiphy_suspend [cfg80211]
>   call phy0+ returned 0 after 7 usecs
> 
> That makes it very obvious what's going on.  It also has the nice side
> effect of making the suspend/resume spew a little more obvious, since
> many resume functions have the word "resume" in the name:
> 
>   calling  phy0+ @ 15793, parent: mmc2:0001:1, cb: wiphy_resume [cfg80211]
>   call phy0+ returned 0 after 12 usecs
>   calling  rfkill1+ @ 15793, parent: phy0, cb: rfkill_resume
>   call rfkill1+ returned 0 after 1 usecs
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> Acked-by: Pavel Machek <pavel@....cz>
> Signed-off-by: Brian Norris <briannorris@...omium.org>

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

> ---
> This is a resend of the following patch (w/ minor $subject alteration):
> 
> https://patchwork.kernel.org/patch/7241641/
> 
> It was useful for debugging the following patch, so I thought I'd resend. It
> received an Ack the first time.
> 
>  drivers/base/power/main.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index e44944f4be77..c58563581345 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -190,14 +190,14 @@ void device_pm_move_last(struct device *dev)
>  	list_move_tail(&dev->power.entry, &dpm_list);
>  }
>  
> -static ktime_t initcall_debug_start(struct device *dev)
> +static ktime_t initcall_debug_start(struct device *dev, void *cb)
>  {
>  	ktime_t calltime = ktime_set(0, 0);
>  
>  	if (pm_print_times_enabled) {
> -		pr_info("calling  %s+ @ %i, parent: %s\n",
> +		pr_info("calling  %s+ @ %i, parent: %s, cb: %pf\n",
>  			dev_name(dev), task_pid_nr(current),
> -			dev->parent ? dev_name(dev->parent) : "none");
> +			dev->parent ? dev_name(dev->parent) : "none", cb);
>  		calltime = ktime_get();
>  	}
>  
> @@ -384,7 +384,7 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev,
>  	if (!cb)
>  		return 0;
>  
> -	calltime = initcall_debug_start(dev);
> +	calltime = initcall_debug_start(dev, cb);
>  
>  	pm_dev_dbg(dev, state, info);
>  	trace_device_pm_callback_start(dev, info, state.event);
> @@ -1330,7 +1330,7 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
>  	int error;
>  	ktime_t calltime;
>  
> -	calltime = initcall_debug_start(dev);
> +	calltime = initcall_debug_start(dev, cb);
>  
>  	trace_device_pm_callback_start(dev, info, state.event);
>  	error = cb(dev, state);
> -- 
> 2.8.0.rc3.226.g39d4020
> 

-- 
Dmitry