linux-kernel - Re: [PATCH v11 4/6] powerpc/papr_scm: Improve error logging and handling papr_scm

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Message-ID: <20200608160747.GA2936401@iweiny-DESK2.sc.intel.com>
Date:   Mon, 8 Jun 2020 09:07:48 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Vaibhav Jain <vaibhav@...ux.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Dan Williams <dan.j.williams@...el.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Oliver O'Halloran <oohall@...il.com>,
        Santosh Sivaraj <santosh@...six.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v11 4/6] powerpc/papr_scm: Improve error logging and
 handling papr_scm_ndctl()

On Sun, Jun 07, 2020 at 06:43:37PM +0530, Vaibhav Jain wrote:
> Since papr_scm_ndctl() can be called from outside papr_scm, its
> exposed to the possibility of receiving NULL as value of 'cmd_rc'
> argument. This patch updates papr_scm_ndctl() to protect against such
> possibility by assigning it pointer to a local variable in case cmd_rc
> == NULL.
> 
> Finally the patch also updates the 'default' add a debug log unknown
> 'cmd' values.
> 
> Cc: "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Ira Weiny <ira.weiny@...el.com>

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> Signed-off-by: Vaibhav Jain <vaibhav@...ux.ibm.com>
> ---
> Changelog:
> 
> v10..v11:
> * Instead of returning *cmd_rd just return '0' in case nd_cmd is
>   handled. In case of unknown nd-cmd return -EINVAL
>   [ Ira and Dan Williams ]
> * Updated patch description.
> 
> v9..v10
> * New patch in the series
> ---
>  arch/powerpc/platforms/pseries/papr_scm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index 0c091622b15e..692ad3d79826 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -355,11 +355,16 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
>  {
>  	struct nd_cmd_get_config_size *get_size_hdr;
>  	struct papr_scm_priv *p;
> +	int rc;
>  
>  	/* Only dimm-specific calls are supported atm */
>  	if (!nvdimm)
>  		return -EINVAL;
>  
> +	/* Use a local variable in case cmd_rc pointer is NULL */
> +	if (!cmd_rc)
> +		cmd_rc = &rc;
> +
>  	p = nvdimm_provider_data(nvdimm);
>  
>  	switch (cmd) {
> @@ -381,6 +386,7 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
>  		break;
>  
>  	default:
> +		dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
>  		return -EINVAL;
>  	}
>  
> -- 
> 2.26.2
>