netdev - [PATCH net-next] net: skb_queue_purge

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Date: Tue,  3 Oct 2023 18:19:20 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net: skb_queue_purge_reason() optimizations

1) Exit early if the list is empty.

2) splice the list into a local list,
   so that we block hard irqs only once.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/skbuff.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 87f5372b197fff4ffef5df34ef126eb1e297ae4c..0401f40973a584ba4a89509b02510c8352bd6fb5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3722,10 +3722,19 @@ EXPORT_SYMBOL(skb_dequeue_tail);
 void skb_queue_purge_reason(struct sk_buff_head *list,
 			    enum skb_drop_reason reason)
 {
-	struct sk_buff *skb;
+	struct sk_buff_head tmp;
+	unsigned long flags;
+
+	if (skb_queue_empty_lockless(list))
+		return;
+
+	__skb_queue_head_init(&tmp);
+
+	spin_lock_irqsave(&list->lock, flags);
+	skb_queue_splice_init(list, &tmp);
+	spin_unlock_irqrestore(&list->lock, flags);
 
-	while ((skb = skb_dequeue(list)) != NULL)
-		kfree_skb_reason(skb, reason);
+	__skb_queue_purge_reason(&tmp, reason);
 }
 EXPORT_SYMBOL(skb_queue_purge_reason);
 
-- 
2.42.0.582.g8ccd20d70d-goog