netdev - [PATCH net-next] net: snmp: fix 64bit stats on 32bit arches

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Message-ID: <1461850404.5535.103.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Thu, 28 Apr 2016 06:33:24 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	nicolas.dichtel@...nd.com
Cc:	Eric Dumazet <edumazet@...gle.com>,
	"David S . Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] net: snmp: fix 64bit stats on 32bit arches

From: Eric Dumazet <edumazet@...gle.com>

I accidentally replaced BH disabling by preemption disabling
in SNMP_ADD_STATS64() and SNMP_UPD_PO_STATS64() on 32bit builds.

For 64bit stats on 32bit arch, we really need to disable BH,
since the "struct u64_stats_sync syncp" might be manipulated
both from process and BH contexts.

Fixes: 6aef70a851ac ("net: snmp: kill various STATS_USER() helpers")
Reported-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Tested-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/snmp.h |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/net/snmp.h b/include/net/snmp.h
index 6bdd255b2250..c9228ad7ee91 100644
--- a/include/net/snmp.h
+++ b/include/net/snmp.h
@@ -166,9 +166,9 @@ struct linux_xfrm_mib {
 
 #define SNMP_ADD_STATS64(mib, field, addend) 				\
 	do {								\
-		preempt_disable();					\
+		local_bh_disable();					\
 		__SNMP_ADD_STATS64(mib, field, addend);			\
-		preempt_enable();					\
+		local_bh_enable();				\
 	} while (0)
 
 #define __SNMP_INC_STATS64(mib, field) SNMP_ADD_STATS64(mib, field, 1)
@@ -184,9 +184,9 @@ struct linux_xfrm_mib {
 	} while (0)
 #define SNMP_UPD_PO_STATS64(mib, basefield, addend)			\
 	do {								\
-		preempt_disable();					\
+		local_bh_disable();					\
 		__SNMP_UPD_PO_STATS64(mib, basefield, addend);		\
-		preempt_enable();					\
+		local_bh_enable();				\
 	} while (0)
 #else
 #define __SNMP_INC_STATS64(mib, field)		__SNMP_INC_STATS(mib, field)