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

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Date:   Mon,  5 Apr 2021 09:57:14 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     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,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] rtlwifi: Simplify locking of a skb list accesses

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 */
-- 
2.27.0