Re: [PATCH] drivers: rewrite and remove a superfluous parameter.

[Arend Van Spriel]

On December 6, 2022 6:59:36 PM Arend Van Spriel 
<arend.vanspriel@xxxxxxxxxxxx> wrote:

> On November 29, 2022 3:06:37 PM Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx>
> wrote:
>
> > On 29/11/2022 06:34, JunASAKA wrote:
> > > I noticed there is a superfluous "*hdr" parameter in rtl8xxxu module
> > > when I am trying to fix some bugs for the rtl8192eu wifi dongle. This
> > > parameter can be removed and then gained from the skb object to make the
> > > function more beautiful.
> > >
> > > Signed-off-by: JunASAKA <JunASAKA@xxxxxxxxxxxxx>
> > > ---
> > > drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 5 +++--
> > > 1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > index ac641a56efb0..4c3d97e8e51f 100644
> > > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > > @@ -4767,9 +4767,10 @@ static u32 rtl8xxxu_80211_to_rtl_queue(u32 queue)
> > > return rtlqueue;
> > > }
> > >
> > > -static u32 rtl8xxxu_queue_select(struct ieee80211_hdr *hdr, struct sk_buff
> > > *skb)
> > > +static u32 rtl8xxxu_queue_select(struct sk_buff *skb)
> > > {
> > > u32 queue;
> > > + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
> > >
> > > if (ieee80211_is_mgmt(hdr->frame_control))
> > > queue = TXDESC_QUEUE_MGNT;
> > > @@ -5118,7 +5119,7 @@ static void rtl8xxxu_tx(struct ieee80211_hw *hw,
> > > if (control && control->sta)
> > > sta = control->sta;
> > >
> > > - queue = rtl8xxxu_queue_select(hdr, skb);
> > > + queue = rtl8xxxu_queue_select(skb);
> > >
> > > tx_desc = skb_push(skb, tx_desc_size);
> >
> > See the recent discussion about this here:
> > https://lore.kernel.org/linux-wireless/acd30174-4541-7343-e49a-badd199f4151@xxxxxxxxx/
> > https://lore.kernel.org/linux-wireless/2af44c28-1c12-46b9-85b9-011560bf7f7e@xxxxxxxxx/
>
> Not sure why I looked but I did. You may want to look at rtl8xxxu_tx()
> which is the .tx callback that mac80211 uses and the first statement in
> there is also assuming skb->data points to the 802.11 header.

Here the documentation of the .tx callback:

@tx: Handler that 802.11 module calls for each transmitted frame.
* skb contains the buffer *starting from the IEEE 802.11 header*.
* The low-level driver should send the frame out based on
* configuration in the TX control data. This handler should,
* preferably, never fail and stop queues appropriately.
* Must be atomic.

I don't see any pushes or pulls before the queue select so that would mean 
mac80211 is not complying to the described behavior.

Regards,
Arend

> Regards,
> Arend
> >

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