net: igmp: increase size of mr_ifc_count

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@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210811195715.3684218-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 53aa034..aaf4f1b 100644 (file)
--- 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 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 */
 
        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 a513600..00576ba 100644 (file)
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -803,7 +803,7 @@ 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);
 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:
 
        igmpv3_send_cr(in_dev);
 restart: