qeth lcs: convert mc rwlock to RCU

Commit 1d7138de878d1d4210727c1200193e69596f93b3
igmp: RCU conversion of in_dev->mc_list

converted rwlock to RCU.

Update the s390 network drivers(qeth & lcs) code to adapt to this change.
V2 : Changes based on suggestions given by Eric Dumazet

Signed-off-by: Sachin Sant <sachinp@in.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c
index 0f19d540b655..c9f13b9ea339 100644
--- a/drivers/s390/net/lcs.c
+++ b/drivers/s390/net/lcs.c
@@ -1188,7 +1188,8 @@ lcs_remove_mc_addresses(struct lcs_card *card, struct in_device *in4_dev)
         spin_lock_irqsave(&card->ipm_lock, flags);
         list_for_each(l, &card->ipm_list) {
                 ipm = list_entry(l, struct lcs_ipm_list, list);
-                for (im4 = in4_dev->mc_list; im4 != NULL; im4 = im4->next) {
+                for (im4 = rcu_dereference(in4_dev->mc_list);
+                     im4 != NULL; im4 = rcu_dereference(im4->next_rcu)) {
                         lcs_get_mac_for_ipm(im4->multiaddr, buf, card->dev);
                         if ( (ipm->ipm.ip_addr == im4->multiaddr) &&
                              (memcmp(buf, &ipm->ipm.mac_addr,
@@ -1233,7 +1234,8 @@ lcs_set_mc_addresses(struct lcs_card *card, struct in_device *in4_dev)
         unsigned long flags;
 
         LCS_DBF_TEXT(4, trace, "setmclst");
-        for (im4 = in4_dev->mc_list; im4; im4 = im4->next) {
+        for (im4 = rcu_dereference(in4_dev->mc_list); im4 != NULL;
+             im4 = rcu_dereference(im4->next_rcu)) {
                 lcs_get_mac_for_ipm(im4->multiaddr, buf, card->dev);
                 ipm = lcs_check_addr_entry(card, im4, buf);
                 if (ipm != NULL)
@@ -1269,10 +1271,10 @@ lcs_register_mc_addresses(void *data)
         in4_dev = in_dev_get(card->dev);
         if (in4_dev == NULL)
                 goto out;
-        read_lock(&in4_dev->mc_list_lock);
+        rcu_read_lock();
         lcs_remove_mc_addresses(card,in4_dev);
         lcs_set_mc_addresses(card, in4_dev);
-        read_unlock(&in4_dev->mc_list_lock);
+        rcu_read_unlock();
         in_dev_put(in4_dev);
 
         netif_carrier_off(card->dev);