From: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: robh+dt@kernel.org, arnd@arndb.de, mark.rutland@arm.com,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
bjorn.andersson@linaro.org, linux-arm-msm@vger.kernel.org,
bkumar@qti.qualcomm.com, thierry.escande@linaro.org
Subject: Re: [PATCH v2 6/6] misc: fastrpc: Add support for compat ioctls
Date: Wed, 12 Dec 2018 12:26:26 +0000 [thread overview]
Message-ID: <9867e420-de78-abc3-ab9d-deea3cf2491e@linaro.org> (raw)
In-Reply-To: <20181212115037.GA31075@kroah.com>
>>>
>>> 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
next prev parent reply other threads:[~2018-12-12 12:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-07 16:35 [PATCH v2 0/6] misc: Add support to Qualcomm FastRPC driver Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 1/6] misc: dt-bindings: Add Qualcomm Fastrpc bindings Srinivas Kandagatla
2018-12-07 18:23 ` Mark Rutland
2018-12-10 11:17 ` Srinivas Kandagatla
2018-12-11 0:10 ` Bjorn Andersson
2018-12-11 9:27 ` Srinivas Kandagatla
2018-12-11 10:50 ` Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 2/6] misc: fastrpc: Add Qualcomm fastrpc basic driver model Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 3/6] misc: fastrpc: Add support for context Invoke method Srinivas Kandagatla
2018-12-10 14:55 ` kbuild test robot
2018-12-12 11:02 ` Greg KH
2018-12-12 11:14 ` Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 4/6] misc: fastrpc: Add support for create remote init process Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 5/6] misc: fastrpc: Add support for dmabuf exporter Srinivas Kandagatla
2018-12-07 16:35 ` [PATCH v2 6/6] misc: fastrpc: Add support for compat ioctls Srinivas Kandagatla
2018-12-12 10:59 ` Greg KH
2018-12-12 11:44 ` Srinivas Kandagatla
2018-12-12 11:50 ` Greg KH
2018-12-12 12:26 ` Srinivas Kandagatla [this message]
2018-12-12 13:41 ` Greg KH
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