[PATCH nf-next 2/9] ipvs: fix sparse warnings for ip_vs_conn listing

[Simon Horman <horms@xxxxxxxxxxxx>]

From: Julian Anastasov <ja@xxxxxx>

kbuild test robot reports for sparse warnings
in commit 088339a57d6042 ("ipvs: convert connection locking"):

net/netfilter/ipvs/ip_vs_conn.c:962:13: warning: context imbalance
        in 'ip_vs_conn_array' - wrong count at exit
include/linux/rcupdate.h:326:30: warning: context imbalance in
        'ip_vs_conn_seq_next' - unexpected unlock
include/linux/rcupdate.h:326:30: warning: context imbalance in
        'ip_vs_conn_seq_stop' - unexpected unlock

Fix it by running ip_vs_conn_array under RCU lock
to avoid conditional locking and by adding proper RCU
annotations.

Signed-off-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
---
 net/netfilter/ipvs/ip_vs_conn.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index de64758..a083bda 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -966,7 +966,6 @@ static void *ip_vs_conn_array(struct seq_file *seq, loff_t 
pos)
        struct ip_vs_iter_state *iter = seq->private;
 
        for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
-               rcu_read_lock();
                hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
                        /* __ip_vs_conn_get() is not needed by
                         * ip_vs_conn_seq_show and ip_vs_conn_sync_seq_show
@@ -977,16 +976,19 @@ static void *ip_vs_conn_array(struct seq_file *seq, 
loff_t pos)
                        }
                }
                rcu_read_unlock();
+               rcu_read_lock();
        }
 
        return NULL;
 }
 
 static void *ip_vs_conn_seq_start(struct seq_file *seq, loff_t *pos)
+       __acquires(RCU)
 {
        struct ip_vs_iter_state *iter = seq->private;
 
        iter->l = NULL;
+       rcu_read_lock();
        return *pos ? ip_vs_conn_array(seq, *pos - 1) :SEQ_START_TOKEN;
 }
 
@@ -1006,28 +1008,24 @@ static void *ip_vs_conn_seq_next(struct seq_file *seq, 
void *v, loff_t *pos)
        e = rcu_dereference(hlist_next_rcu(&cp->c_list));
        if (e)
                return hlist_entry(e, struct ip_vs_conn, c_list);
-       rcu_read_unlock();
 
        idx = l - ip_vs_conn_tab;
        while (++idx < ip_vs_conn_tab_size) {
-               rcu_read_lock();
                hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
                        iter->l = &ip_vs_conn_tab[idx];
                        return cp;
                }
                rcu_read_unlock();
+               rcu_read_lock();
        }
        iter->l = NULL;
        return NULL;
 }
 
 static void ip_vs_conn_seq_stop(struct seq_file *seq, void *v)
+       __releases(RCU)
 {
-       struct ip_vs_iter_state *iter = seq->private;
-       struct hlist_head *l = iter->l;
-
-       if (l)
-               rcu_read_unlock();
+       rcu_read_unlock();
 }
 
 static int ip_vs_conn_seq_show(struct seq_file *seq, void *v)
-- 
1.8.2.1

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