From 5fa85a09390c4a525cb4d06a0c4644b01a47976b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 16 Oct 2017 15:44:36 +0200 Subject: [PATCH] net: core: rcu-ify rtnl af_ops rtnl af_ops currently rely on rtnl mutex: unregister (called from module exit functions) takes the rtnl mutex and all users that do af_ops lookup also take the rtnl mutex. IOW, parallel rmmod will block until doit() callback is done. As none of the af_ops implementation sleep we can use rcu instead. doit functions that need the af_ops can now use rcu instead of the rtnl mutex provided the mutex isn't needed for other reasons. Signed-off-by: Florian Westphal Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 62 ++++++++++++++++++++++++++++++++------------ net/ipv4/devinet.c | 4 +-- 2 files changed, 48 insertions(+), 18 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a49cad25e577..20b550d07fe3 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -453,7 +453,7 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family) { const struct rtnl_af_ops *ops; - list_for_each_entry(ops, &rtnl_af_ops, list) { + list_for_each_entry_rcu(ops, &rtnl_af_ops, list) { if (ops->family == family) return ops; } @@ -470,7 +470,7 @@ static const struct rtnl_af_ops *rtnl_af_lookup(const int family) void rtnl_af_register(struct rtnl_af_ops *ops) { rtnl_lock(); - list_add_tail(&ops->list, &rtnl_af_ops); + list_add_tail_rcu(&ops->list, &rtnl_af_ops); rtnl_unlock(); } EXPORT_SYMBOL_GPL(rtnl_af_register); @@ -482,8 +482,10 @@ EXPORT_SYMBOL_GPL(rtnl_af_register); void rtnl_af_unregister(struct rtnl_af_ops *ops) { rtnl_lock(); - list_del(&ops->list); + list_del_rcu(&ops->list); rtnl_unlock(); + + synchronize_rcu(); } EXPORT_SYMBOL_GPL(rtnl_af_unregister); @@ -496,13 +498,15 @@ static size_t rtnl_link_get_af_size(const struct net_device *dev, /* IFLA_AF_SPEC */ size = nla_total_size(sizeof(struct nlattr)); - list_for_each_entry(af_ops, &rtnl_af_ops, list) { + rcu_read_lock(); + list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) { if (af_ops->get_link_af_size) { /* AF_* + nested data */ size += nla_total_size(sizeof(struct nlattr)) + af_ops->get_link_af_size(dev, ext_filter_mask); } } + rcu_read_unlock(); return size; } @@ -1393,7 +1397,7 @@ static int rtnl_fill_link_af(struct sk_buff *skb, if (!af_spec) return -EMSGSIZE; - list_for_each_entry(af_ops, &rtnl_af_ops, list) { + list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) { struct nlattr *af; int err; @@ -1516,12 +1520,16 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev, nla_put_s32(skb, IFLA_NEW_NETNSID, *new_nsid) < 0) goto nla_put_failure; + rcu_read_lock(); if (rtnl_fill_link_af(skb, dev, ext_filter_mask)) - goto nla_put_failure; + goto nla_put_failure_rcu; + rcu_read_unlock(); nlmsg_end(skb, nlh); return 0; +nla_put_failure_rcu: + rcu_read_unlock(); nla_put_failure: nlmsg_cancel(skb, nlh); return -EMSGSIZE; @@ -1783,17 +1791,27 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[]) nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) { const struct rtnl_af_ops *af_ops; - if (!(af_ops = rtnl_af_lookup(nla_type(af)))) + rcu_read_lock(); + af_ops = rtnl_af_lookup(nla_type(af)); + if (!af_ops) { + rcu_read_unlock(); return -EAFNOSUPPORT; + } - if (!af_ops->set_link_af) + if (!af_ops->set_link_af) { + rcu_read_unlock(); return -EOPNOTSUPP; + } if (af_ops->validate_link_af) { err = af_ops->validate_link_af(dev, af); - if (err < 0) + if (err < 0) { + rcu_read_unlock(); return err; + } } + + rcu_read_unlock(); } } @@ -2251,13 +2269,18 @@ static int do_setlink(const struct sk_buff *skb, nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) { const struct rtnl_af_ops *af_ops; + rcu_read_lock(); + if (!(af_ops = rtnl_af_lookup(nla_type(af)))) BUG(); err = af_ops->set_link_af(dev, af); - if (err < 0) + if (err < 0) { + rcu_read_unlock(); goto errout; + } + rcu_read_unlock(); status |= DO_SETLINK_NOTIFY; } } @@ -4004,25 +4027,30 @@ static int rtnl_fill_statsinfo(struct sk_buff *skb, struct net_device *dev, if (!attr) goto nla_put_failure; - list_for_each_entry(af_ops, &rtnl_af_ops, list) { + rcu_read_lock(); + list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) { if (af_ops->fill_stats_af) { struct nlattr *af; int err; af = nla_nest_start(skb, af_ops->family); - if (!af) + if (!af) { + rcu_read_unlock(); goto nla_put_failure; - + } err = af_ops->fill_stats_af(skb, dev); - if (err == -ENODATA) + if (err == -ENODATA) { nla_nest_cancel(skb, af); - else if (err < 0) + } else if (err < 0) { + rcu_read_unlock(); goto nla_put_failure; + } nla_nest_end(skb, af); } } + rcu_read_unlock(); nla_nest_end(skb, attr); @@ -4091,7 +4119,8 @@ static size_t if_nlmsg_stats_size(const struct net_device *dev, /* for IFLA_STATS_AF_SPEC */ size += nla_total_size(0); - list_for_each_entry(af_ops, &rtnl_af_ops, list) { + rcu_read_lock(); + list_for_each_entry_rcu(af_ops, &rtnl_af_ops, list) { if (af_ops->get_stats_af_size) { size += nla_total_size( af_ops->get_stats_af_size(dev)); @@ -4100,6 +4129,7 @@ static size_t if_nlmsg_stats_size(const struct net_device *dev, size += nla_total_size(0); } } + rcu_read_unlock(); } return size; diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 7ce22a2c07ce..6d9b072d903b 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1757,7 +1757,7 @@ static int inet_validate_link_af(const struct net_device *dev, struct nlattr *a, *tb[IFLA_INET_MAX+1]; int err, rem; - if (dev && !__in_dev_get_rtnl(dev)) + if (dev && !__in_dev_get_rcu(dev)) return -EAFNOSUPPORT; err = nla_parse_nested(tb, IFLA_INET_MAX, nla, inet_af_policy, NULL); @@ -1781,7 +1781,7 @@ static int inet_validate_link_af(const struct net_device *dev, static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla) { - struct in_device *in_dev = __in_dev_get_rtnl(dev); + struct in_device *in_dev = __in_dev_get_rcu(dev); struct nlattr *a, *tb[IFLA_INET_MAX+1]; int rem; -- 2.39.5