[PATCH 4.19 022/131] net: use correct this_cpu primitive in dev_recursion_level

Sasha Levin
2020-06-29T20:16:55Z

From: Florian Westphal <fw@strlen.de>

commit 28b05b92886871bdd8e6a9df73e3a15845fe8ef4 upstream.

syzbot reports:
BUG: using __this_cpu_read() in preemptible code:
caller is dev_recursion_level include/linux/netdevice.h:3052 [inline]
__this_cpu_preempt_check+0x246/0x270 lib/smp_processor_id.c:47
dev_recursion_level include/linux/netdevice.h:3052 [inline]
ip6_skb_dst_mtu include/net/ip6_route.h:245 [inline]

I erronously downgraded a this_cpu_read to __this_cpu_read when
moving dev_recursion_level() around.

Reported-by: syzbot+51471b4aae195285a4a3@syzkaller.appspotmail.com
Fixes: 97cdcf37b57e ("net: place xmit recursion in softnet data")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/netdevice.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 41beebcc61f45..85dc3497c74f1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3001,7 +3001,7 @@ DECLARE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);

static inline int dev_recursion_level(void)
{
- return __this_cpu_read(softnet_data.xmit.recursion);
+ return this_cpu_read(softnet_data.xmit.recursion);
}

#define XMIT_RECURSION_LIMIT 10
--
2.25.1