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-rw-r--r--include/linux/genetlink.h4
-rw-r--r--include/net/genetlink.h5
-rw-r--r--net/netlink/af_netlink.c24
-rw-r--r--net/netlink/af_netlink.h1
-rw-r--r--net/netlink/genetlink.c16
5 files changed, 35 insertions, 15 deletions
diff --git a/include/linux/genetlink.h b/include/linux/genetlink.h
index 55b6857..09460d6 100644
--- a/include/linux/genetlink.h
+++ b/include/linux/genetlink.h
@@ -11,6 +11,10 @@ extern void genl_unlock(void);
extern int lockdep_genl_is_held(void);
#endif
+/* for synchronisation between af_netlink and genetlink */
+extern atomic_t genl_sk_destructing_cnt;
+extern wait_queue_head_t genl_sk_destructing_waitq;
+
/**
* rcu_dereference_genl - rcu_dereference with debug checking
* @p: The pointer to read, prior to dereferencing
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 2ea2c55..6c92415 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -35,7 +35,10 @@ struct genl_info;
* undo operations done by pre_doit, for example release locks
* @mcast_bind: a socket bound to the given multicast group (which
* is given as the offset into the groups array)
- * @mcast_unbind: a socket was unbound from the given multicast group
+ * @mcast_unbind: a socket was unbound from the given multicast group.
+ * Note that unbind() will not be called symmetrically if the
+ * generic netlink family is removed while there are still open
+ * sockets.
* @attrbuf: buffer to store parsed attributes
* @family_list: family list
* @mcgrps: multicast groups used by this family (private)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 84ea76c..02fdde2 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -61,6 +61,7 @@
#include <linux/rhashtable.h>
#include <asm/cacheflush.h>
#include <linux/hash.h>
+#include <linux/genetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@@ -1095,6 +1096,8 @@ static void netlink_remove(struct sock *sk)
__sk_del_bind_node(sk);
netlink_update_listeners(sk);
}
+ if (sk->sk_protocol == NETLINK_GENERIC)
+ atomic_inc(&genl_sk_destructing_cnt);
netlink_table_ungrab();
}
@@ -1211,6 +1214,20 @@ static int netlink_release(struct socket *sock)
* will be purged.
*/
+ /* must not acquire netlink_table_lock in any way again before unbind
+ * and notifying genetlink is done as otherwise it might deadlock
+ */
+ if (nlk->netlink_unbind) {
+ int i;
+
+ for (i = 0; i < nlk->ngroups; i++)
+ if (test_bit(i, nlk->groups))
+ nlk->netlink_unbind(sock_net(sk), i + 1);
+ }
+ if (sk->sk_protocol == NETLINK_GENERIC &&
+ atomic_dec_return(&genl_sk_destructing_cnt) == 0)
+ wake_up(&genl_sk_destructing_waitq);
+
sock->sk = NULL;
wake_up_interruptible_all(&nlk->wait);
@@ -1246,13 +1263,6 @@ static int netlink_release(struct socket *sock)
netlink_table_ungrab();
}
- if (nlk->netlink_unbind) {
- int i;
-
- for (i = 0; i < nlk->ngroups; i++)
- if (test_bit(i, nlk->groups))
- nlk->netlink_unbind(sock_net(sk), i + 1);
- }
kfree(nlk->groups);
nlk->groups = NULL;
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index f123a88..f1c31b3 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -2,6 +2,7 @@
#define _AF_NETLINK_H
#include <linux/rhashtable.h>
+#include <linux/atomic.h>
#include <net/sock.h>
#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index c18d3f5..ee57459 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -23,6 +23,9 @@
static DEFINE_MUTEX(genl_mutex); /* serialization of message processing */
static DECLARE_RWSEM(cb_lock);
+atomic_t genl_sk_destructing_cnt = ATOMIC_INIT(0);
+DECLARE_WAIT_QUEUE_HEAD(genl_sk_destructing_waitq);
+
void genl_lock(void)
{
mutex_lock(&genl_mutex);
@@ -435,15 +438,18 @@ int genl_unregister_family(struct genl_family *family)
genl_lock_all();
- genl_unregister_mc_groups(family);
-
list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
if (family->id != rc->id || strcmp(rc->name, family->name))
continue;
+ genl_unregister_mc_groups(family);
+
list_del(&rc->family_list);
family->n_ops = 0;
- genl_unlock_all();
+ up_write(&cb_lock);
+ wait_event(genl_sk_destructing_waitq,
+ atomic_read(&genl_sk_destructing_cnt) == 0);
+ genl_unlock();
kfree(family->attrbuf);
genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
@@ -1014,7 +1020,6 @@ static int genl_bind(struct net *net, int group)
static void genl_unbind(struct net *net, int group)
{
int i;
- bool found = false;
down_read(&cb_lock);
for (i = 0; i < GENL_FAM_TAB_SIZE; i++) {
@@ -1027,14 +1032,11 @@ static void genl_unbind(struct net *net, int group)
if (f->mcast_unbind)
f->mcast_unbind(net, fam_grp);
- found = true;
break;
}
}
}
up_read(&cb_lock);
-
- WARN_ON(!found);
}
static int __net_init genl_pernet_init(struct net *net)