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[NETLINK]: Switch cb_lock spinlock to mutex and allow to override it

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Switch cb_lock to mutex and allow netlink kernel users to override it
with a subsystem specific mutex for consistent locking in dump callbacks.
All netlink_dump_start users have been audited not to rely on any
side-effects of the previously used spinlock.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy
2007-04-20 14:14:21 -07:00
committed by David S. Miller
parent b076deb849
commit af65bdfce9
20 changed files with 47 additions and 34 deletions
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38
net/netlink/af_netlink.c
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@@ -56,6 +56,7 @@
#include <linux/types.h>
#include <linux/audit.h>
#include <linux/selinux.h>
#include <linux/mutex.h>
#include <net/sock.h>
#include <net/scm.h>
@@ -76,7 +77,8 @@ struct netlink_sock {
unsigned long state;
wait_queue_head_t wait;
struct netlink_callback *cb;
spinlock_t cb_lock;
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
void (*data_ready)(struct sock *sk, int bytes);
struct module *module;
};
@@ -108,6 +110,7 @@ struct netlink_table {
unsigned long *listeners;
unsigned int nl_nonroot;
unsigned int groups;
struct mutex *cb_mutex;
struct module *module;
int registered;
};
@@ -370,7 +373,8 @@ static struct proto netlink_proto = {
.obj_size = sizeof(struct netlink_sock),
};
static int __netlink_create(struct socket *sock, int protocol)
static int __netlink_create(struct socket *sock, struct mutex *cb_mutex,
int protocol)
{
struct sock *sk;
struct netlink_sock *nlk;
@@ -384,7 +388,8 @@ static int __netlink_create(struct socket *sock, int protocol)
sock_init_data(sock, sk);
nlk = nlk_sk(sk);
spin_lock_init(&nlk->cb_lock);
nlk->cb_mutex = cb_mutex ? : &nlk->cb_def_mutex;
mutex_init(nlk->cb_mutex);
init_waitqueue_head(&nlk->wait);
sk->sk_destruct = netlink_sock_destruct;
@@ -395,6 +400,7 @@ static int __netlink_create(struct socket *sock, int protocol)
static int netlink_create(struct socket *sock, int protocol)
{
struct module *module = NULL;
struct mutex *cb_mutex;
struct netlink_sock *nlk;
int err = 0;
@@ -417,9 +423,10 @@ static int netlink_create(struct socket *sock, int protocol)
if (nl_table[protocol].registered &&
try_module_get(nl_table[protocol].module))
module = nl_table[protocol].module;
cb_mutex = nl_table[protocol].cb_mutex;
netlink_unlock_table();
if ((err = __netlink_create(sock, protocol)) < 0)
if ((err = __netlink_create(sock, cb_mutex, protocol)) < 0)
goto out_module;
nlk = nlk_sk(sock->sk);
@@ -444,14 +451,14 @@ static int netlink_release(struct socket *sock)
sock_orphan(sk);
nlk = nlk_sk(sk);
spin_lock(&nlk->cb_lock);
mutex_lock(nlk->cb_mutex);
if (nlk->cb) {
if (nlk->cb->done)
nlk->cb->done(nlk->cb);
netlink_destroy_callback(nlk->cb);
nlk->cb = NULL;
}
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
/* OK. Socket is unlinked, and, therefore,
no new packets will arrive */
@@ -1266,7 +1273,7 @@ static void netlink_data_ready(struct sock *sk, int len)
struct sock *
netlink_kernel_create(int unit, unsigned int groups,
void (*input)(struct sock *sk, int len),
struct module *module)
struct mutex *cb_mutex, struct module *module)
{
struct socket *sock;
struct sock *sk;
@@ -1281,7 +1288,7 @@ netlink_kernel_create(int unit, unsigned int groups,
if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
return NULL;
if (__netlink_create(sock, unit) < 0)
if (__netlink_create(sock, cb_mutex, unit) < 0)
goto out_sock_release;
if (groups < 32)
@@ -1305,6 +1312,7 @@ netlink_kernel_create(int unit, unsigned int groups,
netlink_table_grab();
nl_table[unit].groups = groups;
nl_table[unit].listeners = listeners;
nl_table[unit].cb_mutex = cb_mutex;
nl_table[unit].module = module;
nl_table[unit].registered = 1;
netlink_table_ungrab();
@@ -1347,7 +1355,7 @@ static int netlink_dump(struct sock *sk)
if (!skb)
goto errout;
spin_lock(&nlk->cb_lock);
mutex_lock(nlk->cb_mutex);
cb = nlk->cb;
if (cb == NULL) {
@@ -1358,7 +1366,7 @@ static int netlink_dump(struct sock *sk)
len = cb->dump(skb, cb);
if (len > 0) {
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
skb_queue_tail(&sk->sk_receive_queue, skb);
sk->sk_data_ready(sk, len);
return 0;
@@ -1376,13 +1384,13 @@ static int netlink_dump(struct sock *sk)
if (cb->done)
cb->done(cb);
nlk->cb = NULL;
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
netlink_destroy_callback(cb);
return 0;
errout_skb:
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
kfree_skb(skb);
errout:
return err;
@@ -1414,15 +1422,15 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
}
nlk = nlk_sk(sk);
/* A dump or destruction is in progress... */
spin_lock(&nlk->cb_lock);
mutex_lock(nlk->cb_mutex);
if (nlk->cb || sock_flag(sk, SOCK_DEAD)) {
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
netlink_destroy_callback(cb);
sock_put(sk);
return -EBUSY;
}
nlk->cb = cb;
spin_unlock(&nlk->cb_lock);
mutex_unlock(nlk->cb_mutex);
netlink_dump(sk);
sock_put(sk);