From: Greg KH <gregkh@linuxfoundation.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: ulf.hansson@linaro.org, jassisinghbrar@gmail.com,
s.hauer@pengutronix.de, manohar.vanga@gmail.com,
airlied@linux.ie, linux-hyperv@vger.kernel.org,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
James Bottomley <James.Bottomley@hansenpartnership.com>,
linux1394-devel@lists.sourceforge.net,
anton.ivanov@cambridgegreys.com, devel@driverdev.osuosl.org,
linux-s390@vger.kernel.org, maximlevitsky@gmail.com,
richard@nod.at, deller@gmx.de,
linux-atm-general@lists.sourceforge.net, 3chas3@gmail.com,
linux-input@vger.kernel.org, kuba@kernel.org,
mporter@kernel.crashing.org, jdike@addtoit.com,
Kees Cook <keescook@chromium.org>,
oakad@yahoo.com, intel-gfx@lists.freedesktop.org,
linux-um@lists.infradead.org, linux-block@vger.kernel.org,
broonie@kernel.org, openipmi-developer@lists.sourceforge.net,
mitch@sfgoth.com, linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, netdev@vger.kernel.org,
martyn@welchs.me.uk, dmitry.torokhov@gmail.com,
linux-mmc@vger.kernel.org, Allen Pais <allen.lkml@gmail.com>,
linux-spi@vger.kernel.org, alex.bou9@gmail.com,
Allen Pais <allen.cryptic@gmail.com>,
stefanr@s5r6.in-berlin.de, daniel@ffwll.ch, sre@kernel.org,
linux-ntb@googlegroups.com,
Romain Perier <romain.perier@gmail.com>,
shawnguo@kernel.org, davem@davemloft.net
Subject: Re: [PATCH] block: convert tasklets to use new tasklet_setup() API
Date: Wed, 19 Aug 2020 15:30:39 +0200 [thread overview]
Message-ID: <20200819133039.GA3192753@kroah.com> (raw)
In-Reply-To: <4f5a225d-460f-978f-e3cf-3f505140a515@kernel.dk>
On Wed, Aug 19, 2020 at 07:17:19AM -0600, Jens Axboe wrote:
> On 8/19/20 6:11 AM, Greg KH wrote:
> > On Wed, Aug 19, 2020 at 07:00:53AM -0600, Jens Axboe wrote:
> >> On 8/18/20 1:00 PM, James Bottomley wrote:
> >>> On Mon, 2020-08-17 at 13:02 -0700, Jens Axboe wrote:
> >>>> 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.
> >>>
> >>> 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.
> >
> > I agree, if we want to bike shed, I don't like this color either.
> >
> >> 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.
> >
> > Why are people hating on the well-known and used container_of()?
> >
> > If you really hate to type the type and want a new macro, what about
> > 'container_from()'? (noun/verb is nicer to sort symbols by...)
> >
> > But really, why is this even needed?
>
> container_from() or from_container(), either works just fine for me
> in terms of naming.
>
> I think people are hating on it because it makes for _really_ long
> lines, and it's arguably cleaner/simpler to just pass in the pointer
> type instead. Then you end up with lines like this:
>
> struct request_queue *q =
> container_of(work, struct request_queue, requeue_work.work);
>
> But I'm not the one that started this addition of from_tasklet(), my
> objection was adding a private macro for something that should be
> generic functionality.
Agreed.
> Hence I think we either need to provide that, or
> tell the from_tasklet() folks that they should just use container_of().
Also agreed, thanks.
greg k-h
next prev parent reply other threads:[~2020-08-19 13:30 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 9:15 [PATCH] arch: um: convert tasklets to use new tasklet_setup() API Allen Pais
2020-08-17 9:15 ` [PATCH] block: " Allen Pais
2020-08-17 13:56 ` Jens Axboe
2020-08-17 19:29 ` Kees Cook
2020-08-17 19:44 ` Jens Axboe
2020-08-17 19:48 ` Kees Cook
2020-08-17 20:02 ` Jens Axboe
2020-08-18 20:00 ` James Bottomley
2020-08-18 20:10 ` Kees Cook
2020-08-18 21:00 ` James Bottomley
2020-08-19 10:48 ` Allen
2020-08-19 13:00 ` Jens Axboe
2020-08-19 13:11 ` Greg KH
2020-08-19 13:17 ` Jens Axboe
2020-08-19 13:30 ` Greg KH [this message]
2020-08-19 14:59 ` James Bottomley
2020-08-19 16:24 ` Allen
2020-08-19 16:56 ` Jens Axboe
2020-08-19 21:39 ` James Bottomley
2020-08-26 1:51 ` Allen Pais
2020-08-26 9:55 ` Dan Carpenter
2020-08-26 15:13 ` Kees Cook
2020-08-27 1:37 ` Allen
2020-08-17 9:15 ` [PATCH] char: ipmi: " Allen Pais
2020-08-17 12:15 ` Corey Minyard
2020-08-18 9:16 ` Allen
2020-08-18 11:32 ` Corey Minyard
2020-08-17 9:15 ` [PATCH] driver: hv: " Allen Pais
2020-08-17 9:15 ` [PATCH] drivers: atm: " Allen Pais
2020-08-17 9:16 ` [PATCH] drivers: ntb: " Allen Pais
2020-08-17 9:16 ` [PATCH] drivers: rapidio: " Allen Pais
2020-08-17 9:16 ` [PATCH] drivers: s390: " Allen Pais
2020-08-17 9:16 ` [PATCH] drivers: vme: " Allen Pais
2020-08-17 9:16 ` [PATCH] drm: i915: " Allen Pais
2020-08-17 9:16 ` [PATCH] firewire: ohci: " Allen Pais
2020-08-17 9:16 ` [PATCH 1/2] hsi: nokia-modem: " Allen Pais
2020-08-17 9:16 ` [PATCH] input: serio: " Allen Pais
2020-08-17 9:16 ` [PATCH 1/2] mailbox: bcm: " Allen Pais
2020-08-17 9:16 ` [PATCH 1/2] memstick: jmb38x: " Allen Pais
2020-08-17 9:16 ` [PATCH 1/2] misc: ibmvmc: " Allen Pais
2020-08-17 9:16 ` [PATCH] net: atm: convert tasklets callbacks to use from_tasklet() Allen Pais
2020-08-17 9:16 ` [PATCH] platform: goldfish: convert tasklets to use new tasklet_setup() API Allen Pais
2020-10-18 21:50 ` [PATCH] arch: um: " Richard Weinberger
2020-10-19 7:39 ` Anton Ivanov
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