netdev - [PATCH 12/12] netfilter: nf_queue: place volatile data in own cacheline

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Date:   Tue,  1 Nov 2016 22:26:33 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 12/12] netfilter: nf_queue: place volatile data in own cacheline

From: Florian Westphal <fw@...len.de>

As the comment indicates, the data at the end of nfqnl_instance struct is
written on every queue/dequeue, so it should reside in its own cacheline.

Before this change, 'lock' was in first cacheline so we dirtied both.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nfnetlink_queue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index af832c526048..5379f788a372 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -69,7 +69,7 @@ struct nfqnl_instance {
  * Following fields are dirtied for each queued packet,
  * keep them in same cache line if possible.
  */
-	spinlock_t	lock;
+	spinlock_t	lock	____cacheline_aligned_in_smp;
 	unsigned int	queue_total;
 	unsigned int	id_sequence;		/* 'sequence' of pkt ids */
 	struct list_head queue_list;		/* packets in queue */
-- 
2.1.4