linux-kernel - Re: [PATCH] rtlwifi: use tasklet_setup to initialize rx_work

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Date:   Wed, 27 Jan 2021 17:33:10 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Emil Renner Berthing <kernel@...il.dk>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Ping-Ke Shih <pkshih@...ltek.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Allen Pais <allen.lkml@...il.com>,
        Romain Perier <romain.perier@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] rtlwifi: use tasklet_setup to initialize rx_work_tasklet

Emil Renner Berthing <kernel@...il.dk> writes:

> On Wed, 27 Jan 2021 at 16:20, Kalle Valo <kvalo@...eaurora.org> wrote:
>>
>> Willem de Bruijn <willemdebruijn.kernel@...il.com> writes:
>>
>> > On Wed, Jan 27, 2021 at 5:23 AM Emil Renner Berthing <kernel@...il.dk> wrote:
>> >>
>> >> In commit d3ccc14dfe95 most of the tasklets in this driver was
>> >> updated to the new API. However for the rx_work_tasklet only the
>> >> type of the callback was changed from
>> >>   void _rtl_rx_work(unsigned long data)
>> >> to
>> >>   void _rtl_rx_work(struct tasklet_struct *t).
>> >>
>> >> The initialization of rx_work_tasklet was still open-coded and the
>> >> function pointer just cast into the old type, and hence nothing sets
>> >> rx_work_tasklet.use_callback = true and the callback was still called as
>> >>
>> >>   t->func(t->data);
>> >>
>> >> with uninitialized/zero t->data.
>> >>
>> >> Commit 6b8c7574a5f8 changed the casting of _rtl_rx_work a bit and
>> >> initialized t->data to a pointer to the tasklet cast to an unsigned
>> >> long.
>> >>
>> >> This way calling t->func(t->data) might actually work through all the
>> >> casting, but it still doesn't update the code to use the new tasklet
>> >> API.
>> >>
>> >> Let's use the new tasklet_setup to initialize rx_work_tasklet properly
>> >> and set rx_work_tasklet.use_callback = true so that the callback is
>> >> called as
>> >>
>> >>   t->callback(t);
>> >>
>> >> without all the casting.
>> >>
>> >> Fixes: 6b8c7574a5f8 ("rtlwifi: fix build warning")
>> >> Fixes: d3ccc14dfe95 ("rtlwifi/rtw88: convert tasklets to use new
>> >> tasklet_setup() API")
>> >> Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
>> >
>> > Since the current code works, this could target net-next
>>
>> This should go to wireless-drivers-next, not net-next.
>>
>> > without Fixes tags.
>>
>> Correct, no need for Fixes tag as there's no bug to fix. This is only
>> cleanup AFAICS.

Forgot to mention that I can remove the Fixes tags during commit, so no
need to resend just because of those.

> I can definitely see how you can reasonably disagree, but I would not
> be comfortable having code that only works because the calling
> conventions of all relevant architectures happen to put the first
> unsigned long argument and the first pointer argument in the same
> register.

If there's a bug this patch fixes please explain it clearly in the
commit log. But as I read it (though I admit very quickly) I understood
this is just cleanup.

-- 
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