On 11/07/18 17:48, Ray Jui wrote:

On 7/11/2018 5:34 AM, Wei Yongjun wrote:

quoted

platform_get_resource() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference
a bit later in the code.

This is detected by Coccinelle semantic patch.

@@
expression pdev, res, n, t, e, e1, e2;
@@

res = platform_get_resource(pdev, t, n);
+ if (!res)
+?? return -EINVAL;
... when != res == NULL
e = devm_ioremap_nocache(e1, res->start, e2);

Signed-off-by: Wei Yongjun <redacted>
---

Reviewed-by: Ray Jui <redacted>

Change looks good to me, although the check could have been avoided if
'devm_ioremap_resource' is used on the next line instead of
'devm_ioremap_nocache', where validation of resource pointer is done.

But there's probably a reason why 'devm_ioremap_nocache' was used in
this code here.

I am not sure about that. Both ARM and ARM64 has same definition as
ioremp. However, arch/arm/include/asm/io.h do mention:
"ioremap_nocache() is the same as ioremap() as there are too many device

 drivers using this for device registers, and documentation which tells

 people to use it for such for this to be any different."

You could technically use devm_ioremap_resource if you want.

-- 
Regards,
Sudeep