On Fri, 2017-10-20 at 17:33 +0300, Vasily Averin wrote:
> v2: reported to stable@ because it fixes backported patch.
>
> lockd_up() can call lockd_unregister_notifiers twice:
> inside lockd_start_svc() when it calls lockd_svc_exit_thread()
> and then in error path of lockd_up()
>
> Patch forces lockd_start_svc() to unregister notifiers in all error cases
> and removes extra unregister in error path of lockd_up().
>
> Fixes: cb7d224f82e4 "lockd: unregister notifier blocks if the service ..."
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
> ---
> fs/lockd/svc.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> index b995bdc..f04ecfc 100644
> --- a/fs/lockd/svc.c
> +++ b/fs/lockd/svc.c
> @@ -369,6 +369,7 @@ static int lockd_start_svc(struct svc_serv *serv)
> printk(KERN_WARNING
> "lockd_up: svc_rqst allocation failed, error=%d\n",
> error);
> + lockd_unregister_notifiers();
> goto out_rqst;
> }
>
> @@ -459,13 +460,16 @@ int lockd_up(struct net *net)
> }
>
> error = lockd_up_net(serv, net);
> - if (error < 0)
> - goto err_net;
> + if (error < 0) {
> + lockd_unregister_notifiers();
> + goto err_put;
> + }
>
> error = lockd_start_svc(serv);
> - if (error < 0)
> - goto err_start;
> -
> + if (error < 0) {
> + lockd_down_net(serv, net);
> + goto err_put;
> + }
> nlmsvc_users++;
> /*
> * Note: svc_serv structures have an initial use count of 1,
> @@ -476,12 +480,6 @@ int lockd_up(struct net *net)
> err_create:
> mutex_unlock(&nlmsvc_mutex);
> return error;
> -
> -err_start:
> - lockd_down_net(serv, net);
> -err_net:
> - lockd_unregister_notifiers();
> - goto err_put;
> }
> EXPORT_SYMBOL_GPL(lockd_up);
>
I think this looks right. I really do hate the way that the notifier
handling is sprinkled all over the place in this code (not a comment on
your patch so much as the lockd code in general). I don't see a better
way to do it right offhand though.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>