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On Wed, Apr 17, 2013 at 11:50:46PM +0300, Julian Anastasov wrote:
> 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.
Thanks, this seems correct to me.
I have queued it up in ipvs-next.
>
> Signed-off-by: Julian Anastasov <ja@xxxxxx>
> ---
> net/netfilter/ipvs/ip_vs_conn.c | 14 ++++++--------
> 1 files 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)
> --
> 1.7.3.4
>
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