[PATCH 4.19 21/84] net: igmp: increase size of mr_ifc_count

[Sasha Levin]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit b69dd5b3780a7298bd893816a09da751bc0636f7 ]

Some arches support cmpxchg() on 4-byte and 8-byte only.
Increase mr_ifc_count width to 32bit to fix this problem.

Fixes: 4a2b285e7e10 ("net: igmp: fix data-race in igmp_ifc_timer_expire()")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210811195715.3684218-1-eric.dumazet@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/linux/inetdevice.h | 2 +-
 net/ipv4/igmp.c            | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index a64f21a97369..131f93f8d587 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -41,7 +41,7 @@ struct in_device {
 	unsigned long		mr_qri;		/* Query Response Interval */
 	unsigned char		mr_qrv;		/* Query Robustness Variable */
 	unsigned char		mr_gq_running;
-	unsigned char		mr_ifc_count;
+	u32			mr_ifc_count;
 	struct timer_list	mr_gq_timer;	/* general query timer */
 	struct timer_list	mr_ifc_timer;	/* interface change timer */
 
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 95ec3923083f..dca7fe0ae24a 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -807,7 +807,7 @@ static void igmp_gq_timer_expire(struct timer_list *t)
 static void igmp_ifc_timer_expire(struct timer_list *t)
 {
 	struct in_device *in_dev = from_timer(in_dev, t, mr_ifc_timer);
-	u8 mr_ifc_count;
+	u32 mr_ifc_count;
 
 	igmpv3_send_cr(in_dev);
 restart:
-- 
2.30.2