Re: [PATCH 09/13] PM: wakelock: Abort task freezing if a wake lock is held.

[mark gross <mgross@linux.intel.com>]

On Wed, Feb 04, 2009 at 06:50:22PM -0800, Arve Hjønnevåg wrote:
> Avoids a problem where the device sometimes hangs for 20 seconds
> before the screen is turned on.
>

wouldn't it be better to find out what freeze_task call is blocking and
fix that?

 
> Signed-off-by: Arve Hjønnevåg <arve@android.com>
> ---
>  kernel/power/process.c |   22 +++++++++++++++++-----
>  1 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index ca63401..8388d01 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -13,6 +13,7 @@
>  #include <linux/module.h>
>  #include <linux/syscalls.h>
>  #include <linux/freezer.h>
> +#include <linux/wakelock.h>
>  
>  /* 
>   * Timeout for stopping processes
> @@ -36,6 +37,7 @@ static int try_to_freeze_tasks(bool sig_only)
>  	struct timeval start, end;
>  	u64 elapsed_csecs64;
>  	unsigned int elapsed_csecs;
> +	unsigned int wakeup = 0;
>  
>  	do_gettimeofday(&start);
>  
> @@ -62,6 +64,10 @@ static int try_to_freeze_tasks(bool sig_only)
>  		} while_each_thread(g, p);
>  		read_unlock(&tasklist_lock);
>  		yield();			/* Yield is okay here */
> +		if (todo && has_wake_lock(WAKE_LOCK_SUSPEND)) {
> +			wakeup = 1;
> +			break;
> +		}

this effectivey give the freezing algorithm one shot at putting threads
into a suspend safe state.  arn't you risking bugs on resume by doing
this?

>  		if (time_after(jiffies, end_time))
>  			break;
>  	} while (todo);
> @@ -77,11 +83,17 @@ static int try_to_freeze_tasks(bool sig_only)
>  		 * and caller must call thaw_processes() if something fails),
>  		 * but it cleans up leftover PF_FREEZE requests.
>  		 */
> -		printk("\n");
> -		printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
> -				"(%d tasks refusing to freeze):\n",
> -				elapsed_csecs / 100, elapsed_csecs % 100, todo);
> -		show_state();
> +		if (wakeup) {
> +			printk("\n");
> +			printk(KERN_ERR "Freezing of %s aborted\n",
> +					sig_only ? "user space " : "tasks ");
> +		} else {
> +			printk("\n");
> +			printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
> +					"(%d tasks refusing to freeze):\n",
> +					elapsed_csecs / 100, elapsed_csecs % 100, todo);
> +			show_state();
> +		}
>  		read_lock(&tasklist_lock);
>  		do_each_thread(g, p) {
>  			task_lock(p);
> -- 
> 1.6.1
> 
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