Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] linux/kernel.h: add container_from()
To:     Allen Pais <allen.lkml@gmail.com>, torvalds@linux-foundation.org
Cc:     akpm@linux-foundation.org, keescook@chromium.org,
        tglx@linutronix.de, linux-kernel@vger.kernel.org,
        "James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jens Axboe <axboe@kernel.dk>
References: <20200827013636.149307-1-allen.lkml@gmail.com>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
Message-ID: <2176d7e4-2949-e922-1988-fa5eedfc2220@rasmusvillemoes.dk>
Date:   Thu, 27 Aug 2020 20:07:55 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20200827013636.149307-1-allen.lkml@gmail.com>
Content-Type: text/plain; charset=windows-1252
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 27/08/2020 03.36, Allen Pais wrote:
> Introduce container_from() as a generic helper instead of
> sub-systems defining a private from_* API
> (Eg: from_tasklets recently introduced in
> 12cc923f1ccc: Tasklet: Introduce new initialization API)
> 
> The helper is similar to container_of() in argument order
> with the difference of naming the containing structure instead
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

> of having to specify its type.
> 

> +/**
> + * container_from - cast a member of a structure out to the containing structure
> + * @ptr:	the pointer to the member.
> + * @container:	the type of the container struct.
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This seems to have been copy-pasted from container_of? Shouldn't
@container be the (local) value we're storing into? As in foo =
container_from(..., foo, ...)? Or am I misunderstanding the purpose of this?

[And I think it would read nicer if the bikeshed was called
to_container(), but don't care deeply.]

Rasmus