[PATCH 2/2 nf-next] netfilter: seqadj: print the warning log when fail to add seqadj extension

[fgao]

From: Gao Feng <f...@ikuai8.com>

Print the warning log when fail to add seqadj extension like
nf_ct_acct_ext_add does. It could be helpful to find the problem.

Signed-off-by: Gao Feng <f...@ikuai8.com>
---
 include/net/netfilter/nf_conntrack_seqadj.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/net/netfilter/nf_conntrack_seqadj.h 
b/include/net/netfilter/nf_conntrack_seqadj.h
index 4b33629..d548b9c 100644
--- a/include/net/netfilter/nf_conntrack_seqadj.h
+++ b/include/net/netfilter/nf_conntrack_seqadj.h
@@ -27,7 +27,13 @@ static inline struct nf_conn_seqadj *nfct_seqadj(const 
struct nf_conn *ct)
 
 static inline struct nf_conn_seqadj *nfct_seqadj_ext_add(struct nf_conn *ct)
 {
-       return nf_ct_ext_add(ct, NF_CT_EXT_SEQADJ, GFP_ATOMIC);
+       struct nf_conn_seqadj *seqadj = nf_ct_ext_add(ct, NF_CT_EXT_SEQADJ,
+                                                     GFP_ATOMIC);
+
+       if (!seqadj)
+               pr_warn("failed to add seqadj extension area");
+
+       return seqadj;
 }
 
 int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
-- 
1.9.1