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Subject: Re: [PATCH V6 XRT Alveo 08/20] fpga: xrt: driver infrastructure
To:     Lizhi Hou <lizhi.hou@xilinx.com>, linux-kernel@vger.kernel.org
Cc:     linux-fpga@vger.kernel.org, maxz@xilinx.com,
        sonal.santan@xilinx.com, yliu@xilinx.com, michal.simek@xilinx.com,
        stefanos@xilinx.com, devicetree@vger.kernel.org, mdf@kernel.org,
        robh@kernel.org, Max Zhen <max.zhen@xilinx.com>
References: <20210512015339.5649-1-lizhi.hou@xilinx.com>
 <20210512015339.5649-9-lizhi.hou@xilinx.com>
From:   Tom Rix <trix@redhat.com>
Message-ID: <c6ed9349-1a9a-62a9-521f-a12ec8c4a5a5@redhat.com>
Date:   Thu, 13 May 2021 08:27:17 -0700
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On 5/11/21 6:53 PM, Lizhi Hou wrote:
> Infrastructure code providing APIs for managing leaf driver instance
> groups, facilitating inter-leaf driver calls and root calls.
>
> Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
> Signed-off-by: Max Zhen <max.zhen@xilinx.com>
> Signed-off-by: Lizhi Hou <lizhi.hou@xilinx.com>
> Reviewed-by: Tom Rix <trix@redhat.com>

> +
> +int xrt_subdev_root_request(struct xrt_device *self, u32 cmd, void *arg)
> +{
> +	struct device *dev = DEV(self);
> +	struct xrt_subdev_platdata *pdata = DEV_PDATA(self);
> +
> +	WARN_ON(!pdata->xsp_root_cb);
> +	return (*pdata->xsp_root_cb)(dev->parent, pdata->xsp_root_cb_arg, cmd, arg);

I am running v6 through clang's static analyzer.

It reports this problem

drivers/fpga/xrt/lib/subdev.c:72:9: warning: Called function pointer is 
null (null dereference)
         return (*pdata->xsp_root_cb)(dev->parent, 
pdata->xsp_root_cb_arg, cmd, arg);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Though there is a warn_on, can you also add a

return -EINVAL;

To cover this case?

Tom

> +}