Re: [PATCH v2] ARM: imx: fix error handling

Uwe Kleine-König
2014-05-16T19:31:39Z

Hello Walter,

On Fri, May 16, 2014 at 01:49:10PM +0200, walter harms wrote:
> Am 16.05.2014 13:16, schrieb Emil Goode:
> > Hello Walter,
> >
> > On Fri, May 16, 2014 at 12:40:19PM +0200, walter harms wrote:
> >>
> >>
> >> Am 16.05.2014 11:54, schrieb Emil Goode:
> >>> If we fail to allocate struct platform_device pdev we
> >>> dereference it after the goto label err.
> >>>
> >>> I have rearranged the error handling a bit to fix the issue
> >>> and also make it more clear.
> >>>
> >>> Signed-off-by: Emil Goode <emilgoode@gmail.com>
> >>> ---
> >>> v2: Changed to return -ENOMEM instead of ret where possible and
> >>> updated the subject line.
> >>>
> >>> arch/arm/mach-imx/devices/platform-ipu-core.c | 22 +++++++++++++---------
> >>> 1 file changed, 13 insertions(+), 9 deletions(-)
> >>>
> >>> diff --git a/arch/arm/mach-imx/devices/platform-ipu-core.c b/arch/arm/mach-imx/devices/platform-ipu-core.c
> >>> index fc4dd7c..68f2a4a 100644
> >>> --- a/arch/arm/mach-imx/devices/platform-ipu-core.c
> >>> +++ b/arch/arm/mach-imx/devices/platform-ipu-core.c
> >>> @@ -77,34 +77,38 @@ struct platform_device *__init imx_alloc_mx3_camera(
> >>>
> >>> pdev = platform_device_alloc("mx3-camera", 0);
> >>> if (!pdev)
> >>> - goto err;
> >>> + return ERR_PTR(-ENOMEM);
> >>>
> >>> pdev->dev.dma_mask = kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL);
> >>> if (!pdev->dev.dma_mask)
> >>> - goto err;
> >>> + goto put_pdev;
> >>>
> >>> *pdev->dev.dma_mask = DMA_BIT_MASK(32);
> >>> pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> >>>
> >>> ret = platform_device_add_resources(pdev, res, ARRAY_SIZE(res));
> >>> if (ret)
> >>> - goto err;
> >>> + goto free_dma_mask;
> >>>
> >>> if (pdata) {
> >>> struct mx3_camera_pdata *copied_pdata;
> >>>
> >>> ret = platform_device_add_data(pdev, pdata, sizeof(*pdata));
> >>> - if (ret) {
> >>> -err:
> >>> - kfree(pdev->dev.dma_mask);
> >>> - platform_device_put(pdev);
> >>> - return ERR_PTR(-ENODEV);
> >>> - }
> >>> + if (ret)
> >>> + goto free_dma_mask;
> >>> +
> >>> copied_pdata = dev_get_platdata(&pdev->dev);
> >>> copied_pdata->dma_dev = &imx_ipu_coredev->dev;
> >>
> >>
> >> the patch is fine, but what use is this copied_pdata ?
> >> It scope ends next line ?
> >>
> >> re,
> >> wh
> >
> > I also thought that looked a bit odd, but copied_pdata is a temporary
> > pointer to platform_data of the dev struct.
> >
> > dev_get_platdata looks like this:
> >
> > static inline void *dev_get_platdata(const struct device *dev)
> > {
> > return dev->platform_data;
> > }
> >
> > So I believe it's a more compact way of writing:
> >
> > pdev->dev->platform_data->dma_dev = &imx_ipu_coredev->dev;
It's not about compactness. The dev_get_platdata accessor exists to be
used instead of directly accessing dev->platform_data. I admit a comment
would be nice ...

Anyhow this is all ugly, actually you'd want to have the dma_dev member
already fixed when calling platform_device_add_data. But you cannot
simply do

pdata->dma_dev = &imx_ipu_coredev->dev;
ret = platform_device_add_data(pdev, pdata, sizeof(*pdata));

because *pdata is const.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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