linux-kernel - [PATCH 4.9 127/138] netfilter: nft_queue: use raw_smp_processor

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Message-Id: <20171128100554.796269054@linuxfoundation.org>
Date:   Tue, 28 Nov 2017 11:23:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pablo Neira Ayuso <pablo@...filter.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 127/138] netfilter: nft_queue: use raw_smp_processor_id()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netfilter/nft_queue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/nft_queue.c
+++ b/net/netfilter/nft_queue.c
@@ -38,7 +38,7 @@ static void nft_queue_eval(const struct
 
 	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 {