[18/20] batman-adv: Place kref_get for tvlv_handler near use
Commit Message
From: Sven Eckelmann <sven@narfation.org>
It is hard to understand why the refcnt is increased when it isn't done
near the actual place the new reference is used. So using kref_get right
before the place which requires the reference and in the same function
helps to avoid accidental problems caused by incorrect reference counting.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
net/batman-adv/tvlv.c | 4 ++++
1 file changed, 4 insertions(+)
Comments
On 8/22/2016 4:56 PM, Simon Wunderlich wrote:
> From: Sven Eckelmann <sven@narfation.org>
>
> It is hard to understand why the refcnt is increased when it isn't done
> near the actual place the new reference is used. So using kref_get right
> before the place which requires the reference and in the same function
> helps to avoid accidental problems caused by incorrect reference counting.
Neither does the boilerplate work for this patch...
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
> ---
> net/batman-adv/tvlv.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c
> index 3533867..77654f0 100644
> --- a/net/batman-adv/tvlv.c
> +++ b/net/batman-adv/tvlv.c
> @@ -547,8 +547,12 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv,
> INIT_HLIST_NODE(&tvlv_handler->list);
>
> spin_lock_bh(&bat_priv->tvlv.handler_list_lock);
> + kref_get(&tvlv_handler->refcount);
> hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list);
> spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);
> +
> + /* don't return reference to new tvlv_handler */
> + batadv_tvlv_handler_put(tvlv_handler);
> }
>
> /**
MBR, Sergei
@@ -547,8 +547,12 @@ void batadv_tvlv_handler_register(struct batadv_priv *bat_priv,
INIT_HLIST_NODE(&tvlv_handler->list);
spin_lock_bh(&bat_priv->tvlv.handler_list_lock);
+ kref_get(&tvlv_handler->refcount);
hlist_add_head_rcu(&tvlv_handler->list, &bat_priv->tvlv.handler_list);
spin_unlock_bh(&bat_priv->tvlv.handler_list_lock);
+
+ /* don't return reference to new tvlv_handler */
+ batadv_tvlv_handler_put(tvlv_handler);
}
/**