linux-kernel - Re: [PATCH 1/2]Revert "SCSI: Fix NULL pointer dereference in runtime PM"

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Message-ID: <1448593294.3216.11.camel@amd.com>
Date:	Fri, 27 Nov 2015 03:01:42 +0000
From:	"Xue, Ken" <Ken.Xue@....com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mlin@...nel.org" <mlin@...nel.org>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>
CC:	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"Huang, Shane" <Shane.Huang@....com>,
	SPG_Linux_Kernel <SPG_Linux_Kernel@....com>,
	"aaron.lu@...el.com" <aaron.lu@...el.com>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	"JBottomley@...n.com" <JBottomley@...n.com>,
	"Yu, Xiangliang" <Xiangliang.Yu@....com>
Subject: Re: [PATCH 1/2]Revert "SCSI: Fix NULL pointer dereference in runtime
 PM"

On 四, 2015-09-10 at 10:23 +0800, Ken Xue wrote:

Can someone help to apply this patch series? Thanks.
http://marc.info/?l=linux-scsi&m=144185206825609&w=2
http://marc.info/?l=linux-scsi&m=144185208525611&w=2 

> Revert "SCSI: Fix NULL pointer dereference in runtime PM"
> 
> This reverts commit 49718f0fb8c9 ("SCSI: Fix NULL pointer dereference
> in
> runtime PM")
> 
> The old commit may lead to a issue that
> blk_{pre|post}_runtime_suspend and
> blk_{pre|post}_runtime_resume can not be called in pairs.
> 
> Take sr device as example, when sr device goes to runtime suspend, 
> blk_{pre|post}_runtime_suspend will be called since sr device defined
> pm->runtime_suspend. But blk_{pre|post}_runtime_resume will not be
> called
> since sr device doesn't have pm->runtime_resume. Then sr device can
> not
> resume correctly anymore.
> 
> Signed-off-by: Ken Xue <Ken.Xue@....com>
> Acked-by: Alan Stern <stern@...land.harvard.edu>
> Cc: stable@...r.kernel.org
> 
> ---
>  drivers/scsi/scsi_pm.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
> index e4b7998..459abe1 100644
> --- a/drivers/scsi/scsi_pm.c
> +++ b/drivers/scsi/scsi_pm.c
> @@ -219,13 +219,13 @@ static int sdev_runtime_suspend(struct device
> *dev)
>  	struct scsi_device *sdev = to_scsi_device(dev);
>  	int err = 0;
>  
> -	if (pm && pm->runtime_suspend) {
> -		err = blk_pre_runtime_suspend(sdev->request_queue);
> -		if (err)
> -			return err;
> +	err = blk_pre_runtime_suspend(sdev->request_queue);
> +	if (err)
> +		return err;
> +	if (pm && pm->runtime_suspend)
>  		err = pm->runtime_suspend(dev);
> -		blk_post_runtime_suspend(sdev->request_queue, err);
> -	}
> +	blk_post_runtime_suspend(sdev->request_queue, err);
> +
>  	return err;
>  }
>  
> @@ -248,11 +248,11 @@ static int sdev_runtime_resume(struct device
> *dev)
>  	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm
> : NULL;
>  	int err = 0;
>  
> -	if (pm && pm->runtime_resume) {
> -		blk_pre_runtime_resume(sdev->request_queue);
> +	blk_pre_runtime_resume(sdev->request_queue);
> +	if (pm && pm->runtime_resume)
>  		err = pm->runtime_resume(dev);
> -		blk_post_runtime_resume(sdev->request_queue, err);
> -	}
> +	blk_post_runtime_resume(sdev->request_queue, err);
> +
>  	return err;
>  }
>