Re: [PATCH 3/6] netfilter: ctnetlink: use GFP_ATOMIC in all allocations
From: Eric Dumazet <hidden>
Date: 2012-03-06 12:50:21
Also in:
netfilter-devel
On Tue, 2012-03-06 at 12:22 +0100, pablo@netfilter.org wrote:
quoted hunk ↗ jump to hunk
From: Pablo Neira Ayuso <pablo@netfilter.org> All ctnetlink operations are invoked inside rcu_read_lock (see net/netfilter/nfnetlink.c). Allocations have to be atomic, as RCU requires. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> --- net/netfilter/nf_conntrack_netlink.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 1068769..867843f 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c@@ -1002,7 +1002,7 @@ ctnetlink_get_conntrack(struct sock *ctnl, struct sk_buff *skb, ct = nf_ct_tuplehash_to_ctrack(h); err = -ENOMEM; - skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); if (skb2 == NULL) { nf_ct_put(ct); return -ENOMEM;@@ -1865,7 +1865,7 @@ ctnetlink_get_expect(struct sock *ctnl, struct sk_buff *skb, } err = -ENOMEM; - skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); if (skb2 == NULL) { nf_ct_expect_put(exp); goto out;
This cant be right. Really this must be kept as GFP_KERNEL allocations. Only if .call_rcu member is used in place of .call rcu_read_lock() is held instead of nfnl_lock(). You should take a look at all GFP_ATOMIC uses in net/netfilter/nf_conntrack_netlink.c and check if they can be GFP_KERNEL instead.