Re: [PATCH] block: convert tasklets to use new tasklet_setup() API

From: Jens Axboe <axboe@kernel.dk>
To: Kees Cook <keescook@chromium.org>
Cc: Allen Pais <allen.cryptic@gmail.com>,
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	anton.ivanov@cambridgegreys.com, 3chas3@gmail.com,
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	Allen Pais <allen.lkml@gmail.com>,
	Romain Perier <romain.perier@gmail.com>
Subject: Re: [PATCH] block: convert tasklets to use new tasklet_setup() API
Date: Mon, 17 Aug 2020 13:02:17 -0700	[thread overview]
Message-ID: <df645c06-c30b-eafa-4d23-826b84f2ff48@kernel.dk> (raw)
In-Reply-To: <202008171246.80287CDCA@keescook>

On 8/17/20 12:48 PM, Kees Cook wrote:
> On Mon, Aug 17, 2020 at 12:44:34PM -0700, Jens Axboe wrote:
>> On 8/17/20 12:29 PM, Kees Cook wrote:
>>> On Mon, Aug 17, 2020 at 06:56:47AM -0700, Jens Axboe wrote:
>>>> On 8/17/20 2:15 AM, Allen Pais wrote:
>>>>> From: Allen Pais <allen.lkml@gmail.com>
>>>>>
>>>>> In preparation for unconditionally passing the
>>>>> struct tasklet_struct pointer to all tasklet
>>>>> callbacks, switch to using the new tasklet_setup()
>>>>> and from_tasklet() to pass the tasklet pointer explicitly.
>>>>
>>>> Who came up with the idea to add a macro 'from_tasklet' that is just
>>>> container_of? container_of in the code would be _much_ more readable,
>>>> and not leave anyone guessing wtf from_tasklet is doing.
>>>>
>>>> I'd fix that up now before everything else goes in...
>>>
>>> As I mentioned in the other thread, I think this makes things much more
>>> readable. It's the same thing that the timer_struct conversion did
>>> (added a container_of wrapper) to avoid the ever-repeating use of
>>> typeof(), long lines, etc.
>>
>> But then it should use a generic name, instead of each sub-system using
>> some random name that makes people look up exactly what it does. I'm not
>> huge fan of the container_of() redundancy, but adding private variants
>> of this doesn't seem like the best way forward. Let's have a generic
>> helper that does this, and use it everywhere.
> 
> I'm open to suggestions, but as things stand, these kinds of treewide

On naming? Implementation is just as it stands, from_tasklet() is
totally generic which is why I objected to it. from_member()? Not great
with naming... But I can see this going further and then we'll suddenly
have tons of these. It's not good for readability.

> changes end up getting whole-release delays because of the need to have
> the API in place for everyone before patches to do the changes can be
> sent to multiple maintainers, etc.

Sure, that's always true of treewide changes like that.

-- 
Jens Axboe