linux-kernel - Re: [PATCH] rtlwifi: Simplify locking of a skb list accesses

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Date:   Mon, 5 Apr 2021 11:34:21 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        pkshih@...ltek.com, kvalo@...eaurora.org, davem@...emloft.net,
        kuba@...nel.org
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] rtlwifi: Simplify locking of a skb list accesses

On 4/5/21 2:57 AM, Christophe JAILLET wrote:
> The 'c2hcmd_lock' spinlock is only used to protect some __skb_queue_tail()
> and __skb_dequeue() calls.
> Use the lock provided in the skb itself and call skb_queue_tail() and
> skb_dequeue(). These functions already include the correct locking.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>   drivers/net/wireless/realtek/rtlwifi/base.c | 15 ++-------------
>   drivers/net/wireless/realtek/rtlwifi/wifi.h |  1 -
>   2 files changed, 2 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtlwifi/base.c b/drivers/net/wireless/realtek/rtlwifi/base.c
> index 6e8bd99e8911..2a7ee90a3f54 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/base.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/base.c
> @@ -551,7 +551,6 @@ int rtl_init_core(struct ieee80211_hw *hw)
>   	spin_lock_init(&rtlpriv->locks.rf_lock);
>   	spin_lock_init(&rtlpriv->locks.waitq_lock);
>   	spin_lock_init(&rtlpriv->locks.entry_list_lock);
> -	spin_lock_init(&rtlpriv->locks.c2hcmd_lock);
>   	spin_lock_init(&rtlpriv->locks.scan_list_lock);
>   	spin_lock_init(&rtlpriv->locks.cck_and_rw_pagea_lock);
>   	spin_lock_init(&rtlpriv->locks.fw_ps_lock);
> @@ -2269,7 +2268,6 @@ static bool rtl_c2h_fast_cmd(struct ieee80211_hw *hw, struct sk_buff *skb)
>   void rtl_c2hcmd_enqueue(struct ieee80211_hw *hw, struct sk_buff *skb)
>   {
>   	struct rtl_priv *rtlpriv = rtl_priv(hw);
> -	unsigned long flags;
>   
>   	if (rtl_c2h_fast_cmd(hw, skb)) {
>   		rtl_c2h_content_parsing(hw, skb);
> @@ -2278,11 +2276,7 @@ void rtl_c2hcmd_enqueue(struct ieee80211_hw *hw, struct sk_buff *skb)
>   	}
>   
>   	/* enqueue */
> -	spin_lock_irqsave(&rtlpriv->locks.c2hcmd_lock, flags);
> -
> -	__skb_queue_tail(&rtlpriv->c2hcmd_queue, skb);
> -
> -	spin_unlock_irqrestore(&rtlpriv->locks.c2hcmd_lock, flags);
> +	skb_queue_tail(&rtlpriv->c2hcmd_queue, skb);
>   
>   	/* wake up wq */
>   	queue_delayed_work(rtlpriv->works.rtl_wq, &rtlpriv->works.c2hcmd_wq, 0);
> @@ -2340,16 +2334,11 @@ void rtl_c2hcmd_launcher(struct ieee80211_hw *hw, int exec)
>   {
>   	struct rtl_priv *rtlpriv = rtl_priv(hw);
>   	struct sk_buff *skb;
> -	unsigned long flags;
>   	int i;
>   
>   	for (i = 0; i < 200; i++) {
>   		/* dequeue a task */
> -		spin_lock_irqsave(&rtlpriv->locks.c2hcmd_lock, flags);
> -
> -		skb = __skb_dequeue(&rtlpriv->c2hcmd_queue);
> -
> -		spin_unlock_irqrestore(&rtlpriv->locks.c2hcmd_lock, flags);
> +		skb = skb_dequeue(&rtlpriv->c2hcmd_queue);
>   
>   		/* do it */
>   		if (!skb)
> diff --git a/drivers/net/wireless/realtek/rtlwifi/wifi.h b/drivers/net/wireless/realtek/rtlwifi/wifi.h
> index 9119144bb5a3..877ed6a1589f 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/wifi.h
> +++ b/drivers/net/wireless/realtek/rtlwifi/wifi.h
> @@ -2450,7 +2450,6 @@ struct rtl_locks {
>   	spinlock_t waitq_lock;
>   	spinlock_t entry_list_lock;
>   	spinlock_t usb_lock;
> -	spinlock_t c2hcmd_lock;
>   	spinlock_t scan_list_lock; /* lock for the scan list */
>   
>   	/*FW clock change */
> 

Acked-by: Larry Finger <Larry.Finger@...inger.net>

Thanks,

Larry