[PATCH net-next 7/7] sctp: fix some rhashtable functions using in sctp proc/diag

[Xin Long]

When rhashtable_walk_init return err, no release function should be
called, and when rhashtable_walk_start return err, we should only invoke
rhashtable_walk_exit to release the source.

But now when sctp_transport_walk_start return err, we just call
rhashtable_walk_stop/exit, and never care about if rhashtable_walk_init
or start return err, which is so bad.

We will fix it by calling rhashtable_walk_exit if rhashtable_walk_start
return err in sctp_transport_walk_start, and if sctp_transport_walk_start
return err, we do not need to call sctp_transport_walk_stop any more.

For sctp proc, we will use 'iter->start_fail' to decide if we will call
rhashtable_walk_stop/exit.

Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/proc.c   |  7 ++++++-
 net/sctp/socket.c | 15 ++++++++++-----
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 9fe1393..4cb5aed 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -280,6 +280,7 @@ void sctp_eps_proc_exit(struct net *net)
 struct sctp_ht_iter {
        struct seq_net_private p;
        struct rhashtable_iter hti;
+       int start_fail;
 };
 
 static void *sctp_transport_seq_start(struct seq_file *seq, loff_t *pos)
@@ -287,8 +288,10 @@ static void *sctp_transport_seq_start(struct seq_file 
*seq, loff_t *pos)
        struct sctp_ht_iter *iter = seq->private;
        int err = sctp_transport_walk_start(&iter->hti);
 
-       if (err)
+       if (err) {
+               iter->start_fail = 1;
                return ERR_PTR(err);
+       }
 
        return sctp_transport_get_idx(seq_file_net(seq), &iter->hti, *pos);
 }
@@ -297,6 +300,8 @@ static void sctp_transport_seq_stop(struct seq_file *seq, 
void *v)
 {
        struct sctp_ht_iter *iter = seq->private;
 
+       if (iter->start_fail)
+               return;
        sctp_transport_walk_stop(&iter->hti);
 }
 
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index b0bf6c7..473a40c 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4298,8 +4298,12 @@ int sctp_transport_walk_start(struct rhashtable_iter 
*iter)
                return err;
 
        err = rhashtable_walk_start(iter);
+       if (err && err != -EAGAIN) {
+               rhashtable_walk_exit(iter);
+               return err;
+       }
 
-       return err == -EAGAIN ? 0 : err;
+       return 0;
 }
 
 void sctp_transport_walk_stop(struct rhashtable_iter *iter)
@@ -4388,11 +4392,12 @@ EXPORT_SYMBOL_GPL(sctp_transport_lookup_process);
 int sctp_for_each_transport(int (*cb)(struct sctp_transport *, void *),
                            struct net *net, int pos, void *p) {
        struct rhashtable_iter hti;
-       int err = 0;
        void *obj;
+       int err;
 
-       if (sctp_transport_walk_start(&hti))
-               goto out;
+       err = sctp_transport_walk_start(&hti);
+       if (err)
+               return err;
 
        sctp_transport_get_idx(net, &hti, pos);
        obj = sctp_transport_get_next(net, &hti);
@@ -4406,8 +4411,8 @@ int sctp_for_each_transport(int (*cb)(struct 
sctp_transport *, void *),
                if (err)
                        break;
        }
-out:
        sctp_transport_walk_stop(&hti);
+
        return err;
 }
 EXPORT_SYMBOL_GPL(sctp_for_each_transport);
-- 
2.1.0