On Friday 04 March 2016 16:50:43 Sven Eckelmann wrote:
> On Friday 04 March 2016 16:21:32 Andrew Lunn wrote:
> > Hi
> >
> > I'm sometimes getting a crash after removing a hard interface when the
> > batadv_send_outstanding_bat_org_packet() is called in a work queue.
> > It calls
> >
> > static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
> >
> > int packet_len, unsigned long
> >
> > send_time, bool direct_link,
> >
> > struct batadv_hard_iface
> >
> > *if_incoming, struct batadv_hard_iface *if_outgoing, int own_packet)
> > {
> >
> > struct batadv_priv *bat_priv =
> > netdev_priv(if_incoming->soft_iface);
> >
> > struct batadv_forw_packet *forw_packet_aggr;
> >
> > unsigned char *skb_buff;
> > unsigned int skb_size;
> >
> > if (!kref_get_unless_zero(&if_incoming->refcount))
> >
> > return;
> >
> > if (!kref_get_unless_zero(&if_outgoing->refcount))
> >
> > goto out_free_incoming;
> >
> > Given that we have:
> >
> > static inline void batadv_hardif_put(struct batadv_hard_iface *hard_iface)
> > {
> >
> > kref_put(&hard_iface->refcount, batadv_hardif_release);
> >
> > }
> >
> > does using kref_get_unless_zero() make sense? If it is zero, hasn't it
> > been freed by the kref_put that set it to zero?
Maybe it would be easier to understand when this would be replaced with
kref_get and the if_outgoing loop in batadv_iv_ogm_schedule would be replaced
with:
rcu_read_lock();
list_for_each_entry_rcu(tmp_hard_iface, &batadv_hardif_list, list) {
if (tmp_hard_iface->soft_iface != hard_iface->soft_iface)
continue;
/* make sure only still valid interfaces are used in queue */
if (!kref_get_unless_zero(&tmp_hard_iface->refcount))
continue;
batadv_iv_ogm_queue_add(bat_priv, *ogm_buff,
*ogm_buff_len, hard_iface,
tmp_hard_iface, 1, send_time);
batadv_hardif_put(tmp_hard_iface);
}
rcu_read_unlock();
Sorry for being in noisy-mail mode. I will stop sending mails for today.
Kind regards,
Sven
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