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

Kevin Hilman
2010-01-26T19:00:57Z

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.

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()
+ * @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