RE: [PATCH] wifi: rtl8xxxu: don't call dev_kfree_skb() under spin_lock_irqsave()

[Ping-Ke Shih <pkshih@realtek.com>]

> -----Original Message-----
> From: Yang Yingliang <yangyingliang@huawei.com>
> Sent: Thursday, December 8, 2022 9:26 AM
> To: Ping-Ke Shih <pkshih@realtek.com>; Jes.Sorensen@gmail.com; kvalo@kernel.org
> Cc: linux-wireless@vger.kernel.org; yangyingliang@huawei.com
> Subject: Re: [PATCH] wifi: rtl8xxxu: don't call dev_kfree_skb() under spin_lock_irqsave()
> 
> 
> On 2022/12/8 8:38, Ping-Ke Shih wrote:
> >> -----Original Message-----
> >> From: Yang Yingliang <yangyingliang@huawei.com>
> >> Sent: Wednesday, December 7, 2022 10:38 PM
> >> To: Jes.Sorensen@gmail.com; kvalo@kernel.org
> >> Cc: linux-wireless@vger.kernel.org
> >> Subject: [PATCH] wifi: rtl8xxxu: don't call dev_kfree_skb() under spin_lock_irqsave()
> >>
> >> It is not allowed to call consume_skb() from hardware interrupt context
> >                              ^^^^^^^^^^^^^ kfree_skb()?
> > because this patch is to replace dev_kfree_skb().
> >
> >> or with interrupts being disabled. So replace dev_kfree_skb() with
> >> dev_consume_skb_irq() under spin_lock_irqsave(). Compile tested only.
> >>
> >> Fixes: 26f1fad29ad9 ("New driver: rtl8xxxu (mac80211)")
> >> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> >> ---
> >>   drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> >> b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> >> index ac641a56efb0..d0600af5bef4 100644
> >> --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> >> +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> >> @@ -5274,7 +5274,7 @@ static void rtl8xxxu_queue_rx_urb(struct rtl8xxxu_priv *priv,
> >>   		pending = priv->rx_urb_pending_count;
> >>   	} else {
> >>   		skb = (struct sk_buff *)rx_urb->urb.context;
> >> -		dev_kfree_skb(skb);
> >> +		dev_consume_skb_irq(skb);
> > Why not dev_kfree_skb_irq() instead? any reason?
> #define dev_kfree_skb(a)        consume_skb(a)
> dev_kfree_skb() is consume_skb(), so use dev_consume_skb_irq() instead.
> 
> static inline void dev_kfree_skb_irq(struct sk_buff *skb)
> {
>          __dev_kfree_skb_irq(skb, SKB_REASON_DROPPED);
> }
> 
> static inline void dev_consume_skb_irq(struct sk_buff *skb)
> {
>          __dev_kfree_skb_irq(skb, SKB_REASON_CONSUMED);
> }
> They have different free reasons.
> 

It falls into this case because of 'priv->shutdown', so DROPPED reason makes
sense, no? Or I misunderstand the reason?

--
Ping-Ke