net: ipv6: igmp6_event_query: use msecs_to_jiffies

Use proper API functions to calculate jiffies from milliseconds and
not the crude method of dividing HZ by a value. This ensures more
accurate values even in the case of strange HZ values. While at it,
also simplify code in the mlh2 case by using max().

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 6 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 6c76df9909bf..57863e206d56 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1150,9 +1150,7 @@ int igmp6_event_query(struct sk_buff *skb)
                 int switchback;
                 /* MLDv1 router present */
 
-                /* Translate milliseconds to jiffies */
-                max_delay = (ntohs(mld->mld_maxdelay)*HZ)/1000;
-
+                max_delay = msecs_to_jiffies(ntohs(mld->mld_maxdelay));
                 switchback = (idev->mc_qrv + 1) * max_delay;
                 idev->mc_v1_seen = jiffies + switchback;
 
@@ -1169,10 +1167,11 @@ int igmp6_event_query(struct sk_buff *skb)
                         return -EINVAL;
 
                 mlh2 = (struct mld2_query *)skb_transport_header(skb);
-                max_delay = (MLDV2_MRC(ntohs(mlh2->mld2q_mrc))*HZ)/1000;
-                if (!max_delay)
-                        max_delay = 1;
+
+                max_delay = max(msecs_to_jiffies(MLDV2_MRC(ntohs(mlh2->mld2q_mrc))), 1UL);
+
                 idev->mc_maxdelay = max_delay;
+
                 if (mlh2->mld2q_qrv)
                         idev->mc_qrv = mlh2->mld2q_qrv;
                 if (group_type == IPV6_ADDR_ANY) { /* general query */