Re: [PATCH 1/2] OMAP: omap_device: add omap_device_is_valid()

Paul Walmsley
2010-01-28T00:30:38Z

Hi Kevin,

this looks fine. Two quick comments:

On Tue, 26 Jan 2010, Kevin Hilman wrote:

> The omap_device struct contains a 'struct platform_device'. Normally,
> converting a platform_device pointer to an omap_device pointer
> consists of simply doing a container_of(), as is done currently by the
> to_omap_device() macro.
>
> However, if this is attempted when using platform_device that has not
> been created as part of the omap_device creation, the container_of()
> will point to a memory location before the platform_device pointer
> which will contain random data.
>
> Therefore, we need a way to detect valid omap_device pointers. This
> patch solves this by using the simple magic number approach.

Sounds okay; just FYI at some point in the future, it would be good for
one of us to take a whack at converting omap_device to contain
platform_device, the same way that platform_device contains struct device,
etc..

>
> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
> ---
> Changes from original version:
> - set magic value before omap_device_register()
>
> arch/arm/plat-omap/include/plat/omap_device.h | 2 ++
> arch/arm/plat-omap/omap_device.c | 16 ++++++++++++++++
> 2 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/plat-omap/include/plat/omap_device.h b/arch/arm/plat-omap/include/plat/omap_device.h
> index 76d4917..4677ff7 100644
> --- a/arch/arm/plat-omap/include/plat/omap_device.h
> +++ b/arch/arm/plat-omap/include/plat/omap_device.h
> @@ -62,6 +62,7 @@
> *
> */
> struct omap_device {
> + u32 magic;
> struct platform_device pdev;
> struct omap_hwmod **hwmods;
> struct omap_device_pm_latency *pm_lats;
> @@ -81,6 +82,7 @@ int omap_device_shutdown(struct platform_device *pdev);
>
> /* Core code interface */
>
> +bool omap_device_is_valid(struct omap_device *od);
> int omap_device_count_resources(struct omap_device *od);
> int omap_device_fill_resources(struct omap_device *od, struct resource *res);
>
> diff --git a/arch/arm/plat-omap/omap_device.c b/arch/arm/plat-omap/omap_device.c
> index d8c75c8..187a08f 100644
> --- a/arch/arm/plat-omap/omap_device.c
> +++ b/arch/arm/plat-omap/omap_device.c
> @@ -100,6 +100,8 @@
> # error Unknown OMAP device
> #endif
>
> +#define OMAP_DEVICE_MAGIC 0xf00dcafe
> +
> /* Private functions */
>
> /**
> @@ -413,6 +415,8 @@ struct omap_device *omap_device_build_ss(const char *pdev_name, int pdev_id,
> od->pm_lats = pm_lats;
> od->pm_lats_cnt = pm_lats_cnt;
>
> + od->magic = OMAP_DEVICE_MAGIC;
> +
> ret = omap_device_register(od);
> if (ret)
> goto odbs_exit4;
> @@ -599,6 +603,18 @@ int omap_device_align_pm_lat(struct platform_device *pdev,
> }
>
> /**
> + * omap_device_is_valid()

I think kerneldoc will want a short description after the function name.
Can plug this in here during the merge process if you want...

> + * @od: struct omap_device *
> + *
> + * Return whether struct omap_device pointer @od points to a valid
> + * omap_device.
> + */
> +bool omap_device_is_valid(struct omap_device *od)
> +{
> + return (od && od->magic == OMAP_DEVICE_MAGIC);
> +}
> +
> +/**
> * omap_device_get_pwrdm - return the powerdomain * associated with @od
> * @od: struct omap_device *
> *
> --
> 1.6.6
>
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- Paul