linux-kernel - [PATCH AUTOSEL for 3.18 11/16] netfilter: nft_queue: use raw_smp_processor

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Message-ID: <20171115024607.6064-11-alexander.levin@verizon.com>
Date:   Wed, 15 Nov 2017 02:46:15 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 3.18 11/16] netfilter: nft_queue: use
 raw_smp_processor_id()

From: Pablo Neira Ayuso <pablo@...filter.org>

[ Upstream commit c2e756ff9e699865d294cdc112acfc36419cf5cc ]

Using smp_processor_id() causes splats with PREEMPT_RCU:

[19379.552780] BUG: using smp_processor_id() in preemptible [00000000] code: ping/32389
[19379.552793] caller is debug_smp_processor_id+0x17/0x19
[...]
[19379.552823] Call Trace:
[19379.552832]  [<ffffffff81274e9e>] dump_stack+0x67/0x90
[19379.552837]  [<ffffffff8129a4d4>] check_preemption_disabled+0xe5/0xf5
[19379.552842]  [<ffffffff8129a4fb>] debug_smp_processor_id+0x17/0x19
[19379.552849]  [<ffffffffa07c42dd>] nft_queue_eval+0x35/0x20c [nft_queue]

No need to disable preemption since we only fetch the numeric value, so
let's use raw_smp_processor_id() instead.

Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 net/netfilter/nft_queue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nft_queue.c b/net/netfilter/nft_queue.c
index e8ae2f6bf232..88cd49d3548e 100644
--- a/net/netfilter/nft_queue.c
+++ b/net/netfilter/nft_queue.c
@@ -37,7 +37,7 @@ static void nft_queue_eval(const struct nft_expr *expr,
 
 	if (priv->queues_total > 1) {
 		if (priv->flags & NFT_QUEUE_FLAG_CPU_FANOUT) {
-			int cpu = smp_processor_id();
+			int cpu = raw_smp_processor_id();
 
 			queue = priv->queuenum + cpu % priv->queues_total;
 		} else {
-- 
2.11.0