linux-kernel - Re: [PATCH] PM / Hibernate : Use get_gendisk to verify partition if resume

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Message-Id: <201205122339.01696.rjw@sisk.pl>
Date:	Sat, 12 May 2012 23:39:01 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Minho Ban <mhban@...sung.com>
Cc:	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Rob Landley <rob@...dley.net>, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM / Hibernate : Use get_gendisk to verify partition if resume_file is integer format

On Wednesday, May 09, 2012, Minho Ban wrote:
> Sometimes resume= parameter comes in integer style (e.g. major:minor) then
> name_to_dev_t can not detect partition properly. (especially async device like
> usb, mmc)
> This patch calls get_gendisk if resumewait is true and resume_file is in integer
> format.
> 
> Signed-off-by: Minho Ban <mhban@...sung.com>
> ---
>  Documentation/kernel-parameters.txt |    2 ++
>  kernel/power/hibernate.c            |   13 +++++++++++++
>  2 files changed, 15 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index c1601e5..5900b49 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2372,6 +2372,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  
>  	resume=		[SWSUSP]
>  			Specify the partition device for software suspend
> +			Format:
> +			{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
>  
>  	resume_offset=	[SWSUSP]
>  			Specify the offset from the beginning of the partition
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index e09dfbf..8b53db3 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -25,6 +25,8 @@
>  #include <linux/freezer.h>
>  #include <linux/gfp.h>
>  #include <linux/syscore_ops.h>
> +#include <linux/ctype.h>
> +#include <linux/genhd.h>
>  #include <scsi/scsi_scan.h>
>  
>  #include "power.h"
> @@ -722,6 +724,17 @@ static int software_resume(void)
>  
>  	/* Check if the device is there */
>  	swsusp_resume_device = name_to_dev_t(resume_file);
> +
> +	/*
> +	 * name_to_dev_t is ineffective to verify parition if resume_file is in
> +	 * integer format. (e.g. major:minor)
> +	 */
> +	if (isdigit(resume_file[0]) && resume_wait) {
> +		int partno;
> +		while (!get_gendisk(swsusp_resume_device, &partno))
> +			msleep(10);
> +	}

Hmm.  Wouldn't it be better to do:

	if (isdigit(resume_file[0]) && resume_wait) {
		int partno;
		while (!get_gendisk(swsusp_resume_device, &partno))
			msleep(10);
	} else {
		swsusp_resume_device = name_to_dev_t(resume_file);
	}

?

Your new code will overwrite whatever swsusp_resume_device is set to by the
preceding statement anyway.

> +
>  	if (!swsusp_resume_device) {
>  		/*
>  		 * Some device discovery might still be in progress; we need
> 

Thanks,
Rafael
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