Re: [PATCH] iommu: rockchip: fix building without CONFIG_OF

From: JeffyChen
Date: Wed Apr 04 2018 - 07:05:11 EST

Hi Amd,

Thanks for your patch.

On 04/04/2018 06:23 PM, Arnd Bergmann wrote:
We get a build error when compiling the iommu driver without CONFIG_OF:

drivers/iommu/rockchip-iommu.c: In function 'rk_iommu_of_xlate':
drivers/iommu/rockchip-iommu.c:1101:2: error: implicit declaration of function 'of_dev_put'; did you mean 'of_node_put'? [-Werror=implicit-function-declaration]

oops, didn't notice that.

and checking other iommu drivers which call of_find_device_by_node() too, seems they didn't put() it? maybe we should fix them too

This replaces the of_dev_put() with the equivalent platform_device_put(),
and adds an error check for of_find_device_by_node() returning NULL,
which seems to be appropriate here given that we pass the device into
platform_get_drvdata() next, and that of_find_device_by_node() might
theoretically return a NULL pointer.
hmm, i thought the of_iommu_xlate() checked that before calling us:

static int of_iommu_xlate(struct device *dev,
struct of_phandle_args *iommu_spec)
if ((ops && !ops->of_xlate) ||
!of_device_is_available(iommu_spec->np) ||
(!ops && !of_iommu_driver_present(iommu_spec->np)))
return NO_IOMMU;
return ops->of_xlate(dev, iommu_spec);

but it's better to check it ourself :)

Fixes: 5fd577c3eac3 ("iommu/rockchip: Use OF_IOMMU to attach devices automatically")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
This warning appears to only have been introduced in linux-next after
the merge window opened.
drivers/iommu/rockchip-iommu.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 5fc8656c60f9..fe9c9cc1a9d4 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -1094,11 +1094,15 @@ static int rk_iommu_of_xlate(struct device *dev,
return -ENOMEM;

iommu_dev = of_find_device_by_node(args->np);
+ if (!iommu_dev) {
+ kfree(data);
+ return -ENODEV;
+ }

data->iommu = platform_get_drvdata(iommu_dev);
dev->archdata.iommu = data;

- of_dev_put(iommu_dev);
+ platform_device_put(iommu_dev);

return 0;