linux-kernel - Re: [PATCH 2/7] firmware: add offset to request_firmware_into

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Date:   Thu, 22 Aug 2019 13:07:41 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Brown <david.brown@...aro.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Shuah Khan <shuah@...nel.org>, bjorn.andersson@...aro.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        Olof Johansson <olof@...om.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Colin Ian King <colin.king@...onical.com>,
        Kees Cook <keescook@...omium.org>,
        Takashi Iwai <tiwai@...e.de>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/7] firmware: add offset to request_firmware_into_buf

Hi Luis,

On 2019-08-22 12:47 p.m., Luis Chamberlain wrote:
> On Thu, Aug 22, 2019 at 12:24:46PM -0700, Scott Branden wrote:
>> @@ -923,16 +936,22 @@ EXPORT_SYMBOL_GPL(firmware_request_cache);
>>    */
>>   int
>>   request_firmware_into_buf(const struct firmware **firmware_p, const char *name,
>> -			  struct device *device, void *buf, size_t size)
>> +			  struct device *device, void *buf, size_t size,
>> +			  size_t offset, unsigned int pread_flags)
> This implies you having to change the other callers, and while currently
> our list of drivers is small,

Yes, the list is small, very small.

There is a single driver making a call to the existing API.

And, the existing API was never tested until I submitted a test case.

And, the maintainer of that driver wanted

to start utilizing my enhanced API instead of the current API.

As such I think it is very reasonable to update the API right now.

> following the history of the firmware API
> and the long history of debate of *how* we should evolve its API, its
> preferred we add yet another new caller for this functionality. So
> please add a new caller, and use EXPORT_SYMBOL_GPL().
>
> And while at it, pleaase use firmware_request_*() as the prefix, as we
> have want to use that as the instilled prefix. We have yet to complete
> the rename of the others older callers but its just a matter of time.
>
> So something like: firmware_request_into_buf_offset()

I would prefer to rename the API at this time given there is only a 
single user.

Otherwise I would need to duplicate quite a bit in the test code to 
support testing

the single user of the old api and then enhanced API.

Or, I can leave existing API in place and change the test case to

just test the enhanced API to keep things simpler in the test code?

>
> And thanks for adding a test case!
>
>    Luis

Regards,

  Scott