Le jeudi 18 novembre 2010 Ã 10:33 +0100, Eric Dumazet a Ãcrit :
> Le jeudi 18 novembre 2010 Ã 14:48 +0530, Sachin Sant a Ãcrit :
> > 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.
> >
> > Signed-off-by : Sachin Sant <sachinp@xxxxxxxxxx>
> > ---
> >
> > Only compile tested.
> >
>
> Hmm, sorry but this wont work.
>
> > diff -Narup linux-2.6-next/drivers/s390/net/lcs.c linux-2.6-next-new/drivers/s390/net/lcs.c
> > --- linux-2.6-next/drivers/s390/net/lcs.c 2010-11-17 11:38:25.000000000 +0530
> > +++ linux-2.6-next-new/drivers/s390/net/lcs.c 2010-11-18 11:59:46.000000000 +0530
> > @@ -1269,10 +1269,10 @@ 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();
>
> If you use rcu_read_lock(), then you also need to
> use the rcu list iterators in lcs_remove_mc_addresses() and
> lcs_set_mc_addresses()
>
> Then, its strange this driver is not protected by RTNL at this stage.
>
> Ah yes, it uses a kthread from its ndo_set_multicast_list() handler.
>
> This seems not safe at all.
Please check following patch to give you the idea of what is needed :
diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c
index 0f19d54..05755b7 100644
--- a/drivers/s390/net/lcs.c
+++ b/drivers/s390/net/lcs.c
@@ -1188,7 +1188,9 @@ 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 +1235,9 @@ 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 +1273,10 @@ 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);
--
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