6.6-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit e39951d965bf58b5aba7f61dc1140dcb8271af22 ]
In commit af65bdfce98d ("[NETLINK]: Switch cb_lock spinlock to mutex and allow to override it"), Patrick McHardy used a common mutex to protect both nlk->cb and the dump() operations.
The override is used for rtnl dumps, registered with rntl_register() and rntl_register_module().
We want to be able to opt-out some dump() operations to not acquire RTNL, so we need to protect nlk->cb with a per socket mutex.
This patch renames nlk->cb_def_mutex to nlk->nl_cb_mutex
The optional pointer to the mutex used to protect dump() call is stored in nlk->dump_cb_mutex
Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: 5be2062e3080 ("mpls: Handle error of rtnl_register_module().") Signed-off-by: Sasha Levin sashal@kernel.org --- net/netlink/af_netlink.c | 32 ++++++++++++++++++-------------- net/netlink/af_netlink.h | 5 +++-- 2 files changed, 21 insertions(+), 16 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index db49fc4d42cf7..e40376997f393 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -636,7 +636,7 @@ static struct proto netlink_proto = { };
static int __netlink_create(struct net *net, struct socket *sock, - struct mutex *cb_mutex, int protocol, + struct mutex *dump_cb_mutex, int protocol, int kern) { struct sock *sk; @@ -651,15 +651,11 @@ static int __netlink_create(struct net *net, struct socket *sock, sock_init_data(sock, sk);
nlk = nlk_sk(sk); - if (cb_mutex) { - nlk->cb_mutex = cb_mutex; - } else { - nlk->cb_mutex = &nlk->cb_def_mutex; - mutex_init(nlk->cb_mutex); - lockdep_set_class_and_name(nlk->cb_mutex, + mutex_init(&nlk->nl_cb_mutex); + lockdep_set_class_and_name(&nlk->nl_cb_mutex, nlk_cb_mutex_keys + protocol, nlk_cb_mutex_key_strings[protocol]); - } + nlk->dump_cb_mutex = dump_cb_mutex; init_waitqueue_head(&nlk->wait);
sk->sk_destruct = netlink_sock_destruct; @@ -2211,7 +2207,7 @@ static int netlink_dump(struct sock *sk, bool lock_taken) int alloc_size;
if (!lock_taken) - mutex_lock(nlk->cb_mutex); + mutex_lock(&nlk->nl_cb_mutex); if (!nlk->cb_running) { err = -EINVAL; goto errout_skb; @@ -2263,14 +2259,22 @@ static int netlink_dump(struct sock *sk, bool lock_taken) netlink_skb_set_owner_r(skb, sk);
if (nlk->dump_done_errno > 0) { + struct mutex *extra_mutex = nlk->dump_cb_mutex; + cb->extack = &extack; + + if (extra_mutex) + mutex_lock(extra_mutex); nlk->dump_done_errno = cb->dump(skb, cb); + if (extra_mutex) + mutex_unlock(extra_mutex); + cb->extack = NULL; }
if (nlk->dump_done_errno > 0 || skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) { - mutex_unlock(nlk->cb_mutex); + mutex_unlock(&nlk->nl_cb_mutex);
if (sk_filter(sk, skb)) kfree_skb(skb); @@ -2304,13 +2308,13 @@ static int netlink_dump(struct sock *sk, bool lock_taken) WRITE_ONCE(nlk->cb_running, false); module = cb->module; skb = cb->skb; - mutex_unlock(nlk->cb_mutex); + mutex_unlock(&nlk->nl_cb_mutex); module_put(module); consume_skb(skb); return 0;
errout_skb: - mutex_unlock(nlk->cb_mutex); + mutex_unlock(&nlk->nl_cb_mutex); kfree_skb(skb); return err; } @@ -2333,7 +2337,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, }
nlk = nlk_sk(sk); - mutex_lock(nlk->cb_mutex); + mutex_lock(&nlk->nl_cb_mutex); /* A dump is in progress... */ if (nlk->cb_running) { ret = -EBUSY; @@ -2384,7 +2388,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb, module_put(control->module); error_unlock: sock_put(sk); - mutex_unlock(nlk->cb_mutex); + mutex_unlock(&nlk->nl_cb_mutex); error_free: kfree_skb(skb); return ret; diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h index 2145979b9986a..9751e29d4bbb9 100644 --- a/net/netlink/af_netlink.h +++ b/net/netlink/af_netlink.h @@ -39,8 +39,9 @@ struct netlink_sock { bool cb_running; int dump_done_errno; struct netlink_callback cb; - struct mutex *cb_mutex; - struct mutex cb_def_mutex; + struct mutex nl_cb_mutex; + + struct mutex *dump_cb_mutex; void (*netlink_rcv)(struct sk_buff *skb); int (*netlink_bind)(struct net *net, int group); void (*netlink_unbind)(struct net *net, int group);