From: Jakub Kicinski kuba@kernel.org
[ Upstream commit 5380d64f8d766576ac5c0f627418b2d0e1d2641f ]
Now that we have an intermediate layer of code for handling rtnl-level netlink dump quirks, we can move the rtnl_lock taking there.
For dump handlers with RTNL_FLAG_DUMP_SPLIT_NLM_DONE we can avoid taking rtnl_lock just to generate NLM_DONE, once again.
Signed-off-by: Jakub Kicinski kuba@kernel.org Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/rtnetlink.c | 9 +++++++-- net/netlink/af_netlink.c | 2 -- 2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 4668d67180407..eabfc8290f5e2 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -6486,6 +6486,7 @@ static int rtnl_mdb_del(struct sk_buff *skb, struct nlmsghdr *nlh,
static int rtnl_dumpit(struct sk_buff *skb, struct netlink_callback *cb) { + const bool needs_lock = !(cb->flags & RTNL_FLAG_DUMP_UNLOCKED); rtnl_dumpit_func dumpit = cb->data; int err;
@@ -6495,7 +6496,11 @@ static int rtnl_dumpit(struct sk_buff *skb, struct netlink_callback *cb) if (!dumpit) return 0;
+ if (needs_lock) + rtnl_lock(); err = dumpit(skb, cb); + if (needs_lock) + rtnl_unlock();
/* Old dump handlers used to send NLM_DONE as in a separate recvmsg(). * Some applications which parse netlink manually depend on this. @@ -6515,7 +6520,8 @@ static int rtnetlink_dump_start(struct sock *ssk, struct sk_buff *skb, const struct nlmsghdr *nlh, struct netlink_dump_control *control) { - if (control->flags & RTNL_FLAG_DUMP_SPLIT_NLM_DONE) { + if (control->flags & RTNL_FLAG_DUMP_SPLIT_NLM_DONE || + !(control->flags & RTNL_FLAG_DUMP_UNLOCKED)) { WARN_ON(control->data); control->data = control->dump; control->dump = rtnl_dumpit; @@ -6703,7 +6709,6 @@ static int __net_init rtnetlink_net_init(struct net *net) struct netlink_kernel_cfg cfg = { .groups = RTNLGRP_MAX, .input = rtnetlink_rcv, - .cb_mutex = &rtnl_mutex, .flags = NL_CFG_F_NONROOT_RECV, .bind = rtnetlink_bind, }; diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index fa9c090cf629e..8bbbe75e75dbe 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2330,8 +2330,6 @@ static int netlink_dump(struct sock *sk, bool lock_taken)
cb->extack = &extack;
- if (cb->flags & RTNL_FLAG_DUMP_UNLOCKED) - extra_mutex = NULL; if (extra_mutex) mutex_lock(extra_mutex); nlk->dump_done_errno = cb->dump(skb, cb);