Messages in this thread | | | Subject | Re: [PATCH v2 6/6] misc: fastrpc: Add support for compat ioctls | From | Srinivas Kandagatla <> | Date | Wed, 12 Dec 2018 12:26:26 +0000 |
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>>> >>> What prevents you from doing that and requiring compat support? >>> >> I removed most of the compat IOCTLS except this one. >> The reason is that this ioctl takes arguments which can vary in number for >> each call. > > Then do not do that :) > > Remember, you get to design the api, fix the structure size to work > properly everywhere. > >> So args are passed as pointer to structure, rather than fixed >> size. I could not find better way to rearrange this to give a fixed size >> data structure. In theory number of arguments can vary from 0-255 for both >> in & out. >> >> current data structure looks like this: >> >> struct fastrpc_invoke_args { >> __s32 fd; >> size_t length; >> void *ptr; >> }; > > Make length and ptr both __u64 and you should be fine, right? If you do > that, might as well make fd __u64 as well to align things better. >
That is fine for the args structure, but below "args" pointer in "struct fastrpc_invoke" is still not fixed size, unless we change that to __u64 pointing to array of struct fastrpc_invoke_args. I have seen such usages in i915_drm.h. Is that the preferred?
>> struct fastrpc_invoke { >> __u32 handle; >> __u32 sc; >> struct fastrpc_invoke_args *args; >> }; >>--srini
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