From: Gao feng Subject: [PATCH 01/11] netlink: add reference of module in netlink_dump_start Date: Wed, 26 Sep 2012 12:52:10 +0800 Message-ID: <1348635140-20225-1-git-send-email-gaofeng@cn.fujitsu.com> Cc: netfilter-devel@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, eric.dumazet@gmail.com, pablo@netfilter.org, steffen.klassert@secunet.com, linux-crypto@vger.kernel.org, jengelh@inai.de, stephen.hemminger@vyatta.com, Gao feng To: davem@davemloft.net Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:27694 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750776Ab2IZEwq (ORCPT ); Wed, 26 Sep 2012 00:52:46 -0400 Sender: linux-crypto-owner@vger.kernel.org List-ID: I get a panic when I use ss -a and rmmod inet_diag at the same time. it's because netlink_dump use inet_diag_dump witch function belongs to module inet_diag. I search the codes and find many modules have the same problem. We need add reference of the module witch the cb->dump belongs to. since CONFIG_NET is bool,so netlink_dump_start in rtnetlink.c and genetlink.c will never trigger this problem. Thanks for all help from Stephen,Jan and Eric. Signed-off-by: Gao feng --- include/linux/netlink.h | 4 ++++ net/netlink/af_netlink.c | 25 +++++++++++++++++++++---- 2 files changed, 25 insertions(+), 4 deletions(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index f74dd13..a3641e3 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -232,6 +232,8 @@ struct netlink_callback { struct netlink_callback *cb); int (*done)(struct netlink_callback *cb); void *data; + /* the module that dump function belong to */ + struct module *module; u16 family; u16 min_dump_alloc; unsigned int prev_seq, seq; @@ -251,9 +253,11 @@ struct netlink_dump_control { int (*dump)(struct sk_buff *skb, struct netlink_callback *); int (*done)(struct netlink_callback*); void *data; + struct module *module; u16 min_dump_alloc; }; +extern int netlink_dump_done(struct netlink_callback *cb); extern int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, const struct nlmsghdr *nlh, struct netlink_dump_control *control); diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 5270238..011091c 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1769,6 +1769,14 @@ errout_skb: return err; } +int netlink_dump_done(struct netlink_callback *cb) +{ + if (cb->module) + module_put(cb->module); + return 0; +} +EXPORT_SYMBOL(netlink_dump_done); + int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, const struct nlmsghdr *nlh, struct netlink_dump_control *control) @@ -1786,6 +1794,7 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, cb->done = control->done; cb->nlh = nlh; cb->data = control->data; + cb->module = control->module; cb->min_dump_alloc = control->min_dump_alloc; atomic_inc(&skb->users); cb->skb = skb; @@ -1796,19 +1805,27 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb, return -ECONNREFUSED; } nlk = nlk_sk(sk); - /* A dump is in progress... */ + mutex_lock(nlk->cb_mutex); + /* A dump is in progress... */ if (nlk->cb) { mutex_unlock(nlk->cb_mutex); netlink_destroy_callback(cb); - sock_put(sk); - return -EBUSY; + ret = -EBUSY; + goto out; + } + /* add reference of module witch cb->dump belone to */ + if (cb->module && !try_module_get(cb->module)) { + mutex_unlock(nlk->cb_mutex); + ret = -EPROTONOSUPPORT; + goto out; } + nlk->cb = cb; mutex_unlock(nlk->cb_mutex); ret = netlink_dump(sk); - +out: sock_put(sk); if (ret) -- 1.7.7.6