Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [Linaro-mm-sig] [PATCHv2 4/4] staging: android: ion: Add ioctl to query available heaps | Date | Fri, 02 Sep 2016 23:37:19 +0200 |
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On Friday, September 2, 2016 2:27:21 PM CEST Laura Abbott wrote: > > > > All warnings (new ones prefixed by >>): > > > > drivers/staging/android/ion/ion.c: In function 'ion_query_heaps': > >>> drivers/staging/android/ion/ion.c:1181:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > > (struct ion_heap_data __user *)query->heaps; > > ^ > > > > botching-up-ioctls.txt says: > > * Pointers are __u64, cast from/to a uintprt_t on the userspace side and > from/to a void __user * in the kernel. Try really hard not to delay this > conversion or worse, fiddle the raw __u64 through your code since that > diminishes the checking tools like sparse can provide. > > This doesn't seem like it will work on 32-bit systems since you'll end up > with the warning above. Is there a better option or did I misunderstand > how that is supposed to work? >
I don't know a better way that two cast, doing
(struct ion_heap_data __user *)(uintptr_t)query->heaps;
It may help to put this into an inline function though.
Arnd
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