[net-next:master 195/198] net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

[net-next:master 195/198] net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

[kbuild test robot]

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head:   9ecb9aabaf634677c77af467f4e3028b09d7bcda
commit: ee07c6e7a6f8a25c18f0a6b18152fbd7499245f6 [195/198] bridge: export multicast database via netlink


sparse warnings:

+ net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

vim +79 net/bridge/br_mdb.c

ee07c6e7 Cong Wang 2012-12-07  63  		struct hlist_node *h;
ee07c6e7 Cong Wang 2012-12-07  64  		struct net_bridge_mdb_entry *mp;
ee07c6e7 Cong Wang 2012-12-07  65  		struct net_bridge_port_group *p, **pp;
ee07c6e7 Cong Wang 2012-12-07  66  		struct net_bridge_port *port;
ee07c6e7 Cong Wang 2012-12-07  67  
ee07c6e7 Cong Wang 2012-12-07  68  		hlist_for_each_entry_rcu(mp, h, &mdb->mhash[i], hlist[mdb->ver]) {
ee07c6e7 Cong Wang 2012-12-07  69  			if (idx < s_idx)
ee07c6e7 Cong Wang 2012-12-07  70  				goto skip;
ee07c6e7 Cong Wang 2012-12-07  71  
ee07c6e7 Cong Wang 2012-12-07  72  			nest2 = nla_nest_start(skb, MDBA_MDB_ENTRY);
ee07c6e7 Cong Wang 2012-12-07  73  			if (nest2 == NULL) {
ee07c6e7 Cong Wang 2012-12-07  74  				err = -EMSGSIZE;
ee07c6e7 Cong Wang 2012-12-07  75  				goto out;
ee07c6e7 Cong Wang 2012-12-07  76  			}
ee07c6e7 Cong Wang 2012-12-07  77  
ee07c6e7 Cong Wang 2012-12-07  78  			for (pp = &mp->ports;
ee07c6e7 Cong Wang 2012-12-07 @79  			     (p = rcu_dereference(*pp)) != NULL;
ee07c6e7 Cong Wang 2012-12-07  80  			      pp = &p->next) {
ee07c6e7 Cong Wang 2012-12-07  81  				port = p->port;
ee07c6e7 Cong Wang 2012-12-07  82  				if (port) {
ee07c6e7 Cong Wang 2012-12-07  83  					struct br_mdb_entry e;
ee07c6e7 Cong Wang 2012-12-07  84  					e.ifindex = port->dev->ifindex;
ee07c6e7 Cong Wang 2012-12-07  85  					e.addr.u.ip4 = p->addr.u.ip4;
ee07c6e7 Cong Wang 2012-12-07  86  #if IS_ENABLED(CONFIG_IPV6)
ee07c6e7 Cong Wang 2012-12-07  87  					e.addr.u.ip6 = p->addr.u.ip6;

---
0-DAY kernel build testing backend         Open Source Technology Center
Fengguang Wu, Yuanhan Liu                              Intel Corporation

Re: [net-next:master 195/198] net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

[Cong Wang]

On Sun, 2012-12-09 at 10:54 +0800, kbuild test robot wrote:
> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
> head:   9ecb9aabaf634677c77af467f4e3028b09d7bcda
> commit: ee07c6e7a6f8a25c18f0a6b18152fbd7499245f6 [195/198] bridge: export multicast database via netlink
> 
> 
> sparse warnings:
> 
> + net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

Hi, Fengguang,

I am not sure if I understand this warning correctly. Does the following
patch fix it?

Thanks!

---------------->

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 2528328..0bc0e13 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -77,7 +77,7 @@ static int br_mdb_fill_info(struct sk_buff *skb,
struct netlink_callback *cb,
                        }
 
                        for (pp = &mp->ports;
-                            (p = rcu_dereference(*pp)) != NULL;
+                            (p = rcu_dereference_protected(*pp, 1)) !=
NULL;
                              pp = &p->next) {
                                port = p->port;
                                if (port) {

Re: [net-next:master 195/198] net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)

[Cong Wang]

On Mon, 2012-12-10 at 20:36 +0800, Cong Wang wrote:
> On Sun, 2012-12-09 at 10:54 +0800, kbuild test robot wrote:
> > tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
> > head:   9ecb9aabaf634677c77af467f4e3028b09d7bcda
> > commit: ee07c6e7a6f8a25c18f0a6b18152fbd7499245f6 [195/198] bridge: export multicast database via netlink
> > 
> > 
> > sparse warnings:
> > 
> > + net/bridge/br_mdb.c:79:35: sparse: incompatible types in comparison expression (different address spaces)
> 
> Hi, Fengguang,
> 
> I am not sure if I understand this warning correctly. Does the following
> patch fix it?
> 

Hmm, no, probably this one:

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 2528328..cd6735c 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -63,7 +63,7 @@ static int br_mdb_fill_info(struct sk_buff *skb,
struct netlink_callback *cb,
        for (i = 0; i < mdb->max; i++) {
                struct hlist_node *h;
                struct net_bridge_mdb_entry *mp;
-               struct net_bridge_port_group *p, **pp;
+               struct net_bridge_port_group  __rcu *p, **pp;
                struct net_bridge_port *port;
 
                hlist_for_each_entry_rcu(mp, h, &mdb->mhash[i],
hlist[mdb->ver]) {