netdev - Re: [PATCH net] bridge: Fix VLAN reference count problem

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Message-ID: <8b00288e-221a-e229-e955-6724651d52b1@cumulusnetworks.com>
Date:   Sun, 25 Feb 2018 22:57:18 +0200
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Ido Schimmel <idosch@...lanox.com>, netdev@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Cc:     davem@...emloft.net, stephen@...workplumber.org,
        elena.reshetova@...el.com, mlxsw@...lanox.com
Subject: Re: [PATCH net] bridge: Fix VLAN reference count problem

On 25/02/18 21:59, Ido Schimmel wrote:
> When a VLAN is added on a port, a reference is taken on the
> corresponding master VLAN entry. If it does not already exist, then it
> is created and a reference taken.
> 
> However, in the second case a reference is not really taken when
> CONFIG_REFCOUNT_FULL is enabled as refcount_inc() is replaced by
> refcount_inc_not_zero().
> 
> Fix this by using refcount_set() on a newly created master VLAN entry.
> 
> Fixes: 251277598596 ("net, bridge: convert net_bridge_vlan.refcnt from atomic_t to refcount_t")
> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
> ---
>  net/bridge/br_vlan.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
> index 51935270c651..9896f4975353 100644
> --- a/net/bridge/br_vlan.c
> +++ b/net/bridge/br_vlan.c
> @@ -168,6 +168,8 @@ static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid
>  		masterv = br_vlan_find(vg, vid);
>  		if (WARN_ON(!masterv))
>  			return NULL;
> +		refcount_set(&masterv->refcnt, 1);
> +		return masterv;
>  	}
>  	refcount_inc(&masterv->refcnt);
>  
> 

Good catch,

Acked-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>