linux-kernel - Re: [PATCH net-next 1/2] wireless: Remove casts of void *

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Date:	Tue, 14 Jun 2011 15:39:32 +1000
From:	Julian Calaby <julian.calaby@...il.com>
To:	Joe Perches <joe@...ches.com>
Cc:	netdev@...r.kernel.org,
	"Luis R. Rodriguez" <lrodriguez@...eros.com>,
	Jouni Malinen <jmalinen@...eros.com>,
	Vasanthakumar Thiagarajan <vasanth@...eros.com>,
	Senthil Balasubramanian <senthilkumar@...eros.com>,
	"John W. Linville" <linville@...driver.com>,
	Christian Lamparter <chunkeey@...glemail.com>,
	Stanislaw Gruszka <sgruszka@...hat.com>,
	Wey-Yi Guy <wey-yi.w.guy@...el.com>,
	Intel Linux Wireless <ilw@...ux.intel.com>,
	linux-wireless@...r.kernel.org, ath9k-devel@...ts.ath9k.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] wireless: Remove casts of void *

Joe,

On Tue, Jun 14, 2011 at 15:32, Joe Perches <joe@...ches.com> wrote:
> On Tue, 2011-06-14 at 15:23 +1000, Julian Calaby wrote:
>> Joe,
>
> Hi Julian.
>
>> On Tue, Jun 14, 2011 at 14:02, Joe Perches <joe@...ches.com> wrote:
>> > Unnecessary casts of void * clutter the code.
>> > These are the remainder casts after several specific
>> > patches to remove netdev_priv and dev_priv.
>> You seem to have removed a lot of casts that don't relate to these cleanups.
>> In particular, some of the casts seem to relate more to documentation
>> rather than just changing pointer types to make the compiler happy.
>
> All of the cast removals are casts of void* types.
> I think none of of the casts are useful.
> None of them are required, all are duplicative.

My issue here is that you mention in the commit log that this relates
to the removal of netdev_priv and dev_priv, but the casts removed
(mostly) don't.

>> In
>> particular, I'm referring to the casts describing the different usages
>> of data_buf in mwiflex, and around some pointer math in ath9k.
>
> Can you describe more in detail why you think these are documentary?
>
> This sort of cast:
>
> diff --git a/drivers/net/wireless/mwifiex/11n.c b/drivers/net/wireless/mwifiex/11n.c
> @@ -191,7 +191,7 @@ int mwifiex_ret_11n_cfg(struct host_cmd_ds_command *resp, void *data_buf)
>        struct host_cmd_ds_11n_cfg *htcfg = &resp->params.htcfg;
>
>        if (data_buf) {
> -               tx_cfg = (struct mwifiex_ds_11n_tx_cfg *) data_buf;
> +               tx_cfg = data_buf;
>
> I think pretty useless.  tx_cfg is a struct mwifiex_ds_11n_tx_cfg *.

True, but IMHO, this documents, particularly in a random snippet like
this, what's going on. Arguably though, a better fix would be to move
the cast to the place where this function is called.

>> Whilst I'm sure that the compiler is smart enough to handle automatic
>> casts between pointer types, some of these, in particular the mwiflex
>> bits, add some documentation to the code.
>
> I think not.  Opinions of course can vary.

Of course. I rarely look at full files, so the more information that
can be stuffed into a patch, the better for me. That said, I agree
that all the casts removed are superfluous.

Thanks,

-- 
Julian Calaby

Email: julian.calaby@...il.com
Profile: http://www.google.com/profiles/julian.calaby/
.Plan: http://sites.google.com/site/juliancalaby/
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