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;
MIME-Version: 1.0
References: <161b75f1-4e88-dcdf-42e8-b22504d7525c@kernel.dk>
 <202008171246.80287CDCA@keescook> <df645c06-c30b-eafa-4d23-826b84f2ff48@kernel.dk>
 <1597780833.3978.3.camel@HansenPartnership.com> <f3312928-430c-25f3-7112-76f2754df080@kernel.dk>
 <1597849185.3875.7.camel@HansenPartnership.com> <CAOMdWSJRR0BhjJK1FxD7UKxNd5sk4ycmEX6TYtJjRNR6UFAj6Q@mail.gmail.com>
 <1597873172.4030.2.camel@HansenPartnership.com> <CAEogwTCH8qqjAnSpT0GDn+NuAps8dNbfcPVQ9h8kfOWNbzrD0w@mail.gmail.com>
 <20200826095528.GX1793@kadam> <202008260811.1CE425B5C2@keescook>
In-Reply-To: <202008260811.1CE425B5C2@keescook>
From:   Allen <allen.lkml@gmail.com>
Date:   Thu, 27 Aug 2020 07:07:47 +0530
Message-ID: <CAOMdWSLyacdeoqnZBuLu6z1B6cY-WbtUJQm6+8=WHyE49tVaEg@mail.gmail.com>
Subject: Re: [PATCH] block: convert tasklets to use new tasklet_setup() API
To:     Kees Cook <keescook@chromium.org>
Cc:     Dan Carpenter <dan.carpenter@oracle.com>,
        Allen Pais <allen.cryptic@gmail.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        linux-atm-general@lists.sourceforge.net, manohar.vanga@gmail.com,
        airlied@linux.ie, linux-hyperv@vger.kernel.org,
        dri-devel@lists.freedesktop.org, sre@kernel.org,
        anton.ivanov@cambridgegreys.com, devel@driverdev.osuosl.org,
        linux-s390@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
        maximlevitsky@gmail.com, richard@nod.at, deller@gmx.de,
        jassisinghbrar@gmail.com, linux-spi@vger.kernel.org,
        3chas3@gmail.com, intel-gfx@lists.freedesktop.org,
        Jakub Kicinski <kuba@kernel.org>, mporter@kernel.crashing.org,
        jdike@addtoit.com, oakad@yahoo.com, s.hauer@pengutronix.de,
        linux-input@vger.kernel.org, linux-um@lists.infradead.org,
        linux-block@vger.kernel.org, Mark Brown <broonie@kernel.org>,
        openipmi-developer@lists.sourceforge.net, mitch@sfgoth.com,
        linux-arm-kernel@lists.infradead.org, Jens Axboe <axboe@kernel.dk>,
        linux-parisc@vger.kernel.org, netdev@vger.kernel.org,
        martyn@welchs.me.uk, dmitry.torokhov@gmail.com,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        alex.bou9@gmail.com, stefanr@s5r6.in-berlin.de,
        Daniel Vetter <daniel@ffwll.ch>, linux-ntb@googlegroups.com,
        Romain Perier <romain.perier@gmail.com>, shawnguo@kernel.org,
        David Miller <davem@davemloft.net>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Aug 26, 2020 at 8:43 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Aug 26, 2020 at 12:55:28PM +0300, Dan Carpenter wrote:
> > On Wed, Aug 26, 2020 at 07:21:35AM +0530, Allen Pais wrote:
> > > On Thu, Aug 20, 2020 at 3:09 AM James Bottomley
> > > <James.Bottomley@hansenpartnership.com> wrote:
> > > >
> > > > On Wed, 2020-08-19 at 21:54 +0530, Allen wrote:
> > > > > > [...]
> > > > > > > > Since both threads seem to have petered out, let me suggest in
> > > > > > > > kernel.h:
> > > > > > > >
> > > > > > > > #define cast_out(ptr, container, member) \
> > > > > > > >     container_of(ptr, typeof(*container), member)
> > > > > > > >
> > > > > > > > It does what you want, the argument order is the same as
> > > > > > > > container_of with the only difference being you name the
> > > > > > > > containing structure instead of having to specify its type.
> > > > > > >
> > > > > > > Not to incessantly bike shed on the naming, but I don't like
> > > > > > > cast_out, it's not very descriptive. And it has connotations of
> > > > > > > getting rid of something, which isn't really true.
> > > > > >
> > > > > > Um, I thought it was exactly descriptive: you're casting to the
> > > > > > outer container.  I thought about following the C++ dynamic casting
> > > > > > style, so out_cast(), but that seemed a bit pejorative.  What about
> > > > > > outer_cast()?
> > > > > >
> > > > > > > FWIW, I like the from_ part of the original naming, as it has
> > > > > > > some clues as to what is being done here. Why not just
> > > > > > > from_container()? That should immediately tell people what it
> > > > > > > does without having to look up the implementation, even before
> > > > > > > this becomes a part of the accepted coding norm.
> > > > > >
> > > > > > I'm not opposed to container_from() but it seems a little less
> > > > > > descriptive than outer_cast() but I don't really care.  I always
> > > > > > have to look up container_of() when I'm using it so this would just
> > > > > > be another macro of that type ...
> > > > > >
> > > > >
> > > > >  So far we have a few which have been suggested as replacement
> > > > > for from_tasklet()
> > > > >
> > > > > - out_cast() or outer_cast()
> > > > > - from_member().
> > > > > - container_from() or from_container()
> > > > >
> > > > > from_container() sounds fine, would trimming it a bit work? like
> > > > > from_cont().
> > > >
> > > > I'm fine with container_from().  It's the same form as container_of()
> > > > and I think we need urgent agreement to not stall everything else so
> > > > the most innocuous name is likely to get the widest acceptance.
> > >
> > > Kees,
> > >
> > >   Will you be  sending the newly proposed API to Linus? I have V2
> > > which uses container_from()
> > > ready to be sent out.
> >
> > I liked that James swapped the first two arguments so that it matches
> > container_of().  Plus it's nice that when you have:
> >
> >       struct whatever *foo = container_from(ptr, foo, member);
> >
> > Then it means that "ptr == &foo->member".
>
> I'm a bit stalled right now -- the merge window was keeping me busy, and
> this week is the Linux Plumbers Conference. This is on my list, but I
> haven't gotten back around to it. If you want, feel free to send the
> container_from() patch; you might be able to unblock this faster than me
> right now. :)
>

Sure, Thanks.


-- 
       - Allen