[ovs-dev] [PATCH 1/2] lacp: Don't lock potentially uninitialized mutex in lacp_status().

Andy Zhou azhou at nicira.com
Fri Apr 25 06:03:16 UTC 2014


Acked-by: Andy Zhou <azhou at nicira.com>

With a question inline.


On Thu, Apr 24, 2014 at 4:59 PM, Ben Pfaff <blp at nicira.com> wrote:
> If the 'lacp' parameter is nonnull, then we know that the file scope mutex
> has been initialized, since that's done as a side effect of creating a
> lacp object, but otherwise there's no guarantee.
>
> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
>  lib/lacp.c |   18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/lib/lacp.c b/lib/lacp.c
> index 4aee64f..49ae5e5 100644
> --- a/lib/lacp.c
> +++ b/lib/lacp.c
> @@ -345,18 +345,18 @@ out:
>  enum lacp_status
>  lacp_status(const struct lacp *lacp) OVS_EXCLUDED(mutex)
>  {
> -    enum lacp_status ret;
> +    if (lacp) {
> +        enum lacp_status ret;
>
> -    ovs_mutex_lock(&mutex);
> -    if (!lacp) {
> -        ret = LACP_DISABLED;
> -    } else if (lacp->negotiated) {
> -        ret = LACP_NEGOTIATED;
> +        ovs_mutex_lock(&mutex);
> +        ret = lacp->negotiated ? LACP_NEGOTIATED : LACP_CONFIGURED;
> +        ovs_mutex_unlock(&mutex);
> +        return ret;
>      } else {
> -        ret = LACP_CONFIGURED;
> +        /* Don't take 'mutex'.  It might not even be initialized, since we
> +         * don't know that any lacp object has been created. */
> +        return LACP_DISABLED;
This would have been hard to understand without the comment above.
Thanks for adding them.
I am curious why not just initialize the mutex in lacp_init()?
>      }
> -    ovs_mutex_unlock(&mutex);
> -    return ret;
>  }
>
>  /* Registers 'slave_' as subordinate to 'lacp'.  This should be called at least
> --
> 1.7.10.4
>
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