Alex, 

Did you consider simply taking a reference instead of the mutex? pros/cons?

  Jarno

On Nov 25, 2014, at 4:01 PM, Alex Wang <al...@nicira.com> wrote:

> On current master, the 'struct dp_netdev_port' is destroyed
> immediately when the ref count reaches 0.  However, non-pmd
> threads calling the dpif_netdev_execute() for sending packets
> could hold pointer to 'port' that is not ref-counted.  Thusly
> those threads could possibly access freed memory when the port
> is deleted.
> 
> To fix this bug, this commit makes non-pmd threads acquiring
> the 'port_mutex' before doing the actual execution in
> dpif_netdev_execute().
> 
> Signed-off-by: Alex Wang <al...@nicira.com>
> ---
> lib/dpif-netdev.c |    2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index ea87023..5233130 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -2029,10 +2029,12 @@ dpif_netdev_execute(struct dpif *dpif, struct 
> dpif_execute *execute)
>      * the 'non_pmd_mutex'. */
>     if (pmd->core_id == NON_PMD_CORE_ID) {
>         ovs_mutex_lock(&dp->non_pmd_mutex);
> +        ovs_mutex_lock(&dp->port_mutex);
>     }
>     dp_netdev_execute_actions(pmd, &pp, 1, false, execute->actions,
>                               execute->actions_len);
>     if (pmd->core_id == NON_PMD_CORE_ID) {
> +        ovs_mutex_unlock(&dp->port_mutex);
>         ovs_mutex_unlock(&dp->non_pmd_mutex);
>     }
> 
> -- 
> 1.7.9.5
> 
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