Subject: Re: [PATCH v2 20/30] cxlflash: Correct usage of scsi_host_put()

From: Brian King <[email-masked]>
Date: Tue, 22 Sep 2015 15:53:06 -0500

On 09/16/2015 04:30 PM, Matthew R. Ochs wrote:
> Currently, scsi_host_put() is being called prematurely in the
> remove path and is missing entirely in an error cleanup path.
> The former can lead to memory being freed too early with
> subsequent access potentially corrupting data whilst the former
> would result in a memory leak.
> 
> Move the usage on remove to be the last cleanup action taken
> and introduce a call to scsi_host_put() in the one initialization
> error path that does not use remove to cleanup.
> 
> Signed-off-by: Matthew R. Ochs <[email-masked]>
> Signed-off-by: Manoj N. Kumar <[email-masked]>
> ---
>  drivers/scsi/cxlflash/main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
> index fc77cd4..1856a73 100644
> --- a/drivers/scsi/cxlflash/main.c
> +++ b/drivers/scsi/cxlflash/main.c
> @@ -734,7 +734,6 @@ static void cxlflash_remove(struct pci_dev *pdev)
>  	case INIT_STATE_SCSI:
>  		cxlflash_term_local_luns(cfg);
>  		scsi_remove_host(cfg->host);
> -		scsi_host_put(cfg->host);
>  		/* Fall through */
>  	case INIT_STATE_AFU:
>  		term_afu(cfg);
> @@ -744,6 +743,7 @@ static void cxlflash_remove(struct pci_dev *pdev)
>  	case INIT_STATE_NONE:
>  		flush_work(&cfg->work_q);
>  		free_mem(cfg);
> +		scsi_host_put(cfg->host);
>  		break;
>  	}
> 
> @@ -2415,6 +2415,7 @@ static int cxlflash_probe(struct pci_dev *pdev,
>  		dev_err(&pdev->dev, "%s: call to scsi_host_alloc failed!\n",

This message text is wrong. Its the call to alloc_mem that has failed in this
leg, not the call to scsi_host_alloc.

>  			__func__);
>  		rc = -ENOMEM;
> +		scsi_host_put(cfg->host);
>  		goto out;
>  	}
> 

-- 
Brian King
Power Linux I/O
IBM Linux Technology Center