From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754385AbdIHGC7 (ORCPT ); Fri, 8 Sep 2017 02:02:59 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35790 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753126AbdIHGC5 (ORCPT ); Fri, 8 Sep 2017 02:02:57 -0400 X-Google-Smtp-Source: ADKCNb6hIAFrvaX2WYm1o3Oywk9FJcPBqhzq3vP21Wi0gabKGDcSGeimRN/hDE2TdJ7aMqoXVMaCRw== Subject: [PATCH 3/3] net: skb_queue_purge(): lock/unlock the list only once Date: Fri, 08 Sep 2017 05:06:30 -0000 From: Michael Witten To: "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <60c8906b751d4915be456009c220516e-mfwitten@gmail.com> In-Reply-To: <45aab5effc0c424a992646a97cf2ec14-mfwitten@gmail.com> References: <45aab5effc0c424a992646a97cf2ec14-mfwitten@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Date: Thu, 7 Sep 2017 20:07:40 +0000 With this commit, the list's lock is locked/unlocked only once for the duration of `skb_queue_purge()'. Hitherto, the list's lock has been locked/unlocked every time an item is dequeued; this seems not only inefficient, but also incorrect, as the whole point of `skb_queue_purge()' is to clear the list, presumably without giving anything else a chance to manipulate the list in the interim. Signed-off-by: Michael Witten --- net/core/skbuff.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 68065d7d383f..66c0731a2a5f 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2834,9 +2834,13 @@ EXPORT_SYMBOL(skb_dequeue_tail); */ void skb_queue_purge(struct sk_buff_head *list) { + unsigned long flags; struct sk_buff *skb; - while ((skb = skb_dequeue(list)) != NULL) + + spin_lock_irqsave(&list->lock, flags); + while ((skb = __skb_dequeue(list)) != NULL) kfree_skb(skb); + spin_unlock_irqrestore(&list->lock, flags); } EXPORT_SYMBOL(skb_queue_purge); -- 2.14.1