[dm-devel] [PATCH] multipathd: fix no checking persistent reservation registration

[Martin Wilck]

On Do, 2021-06-24 at 16:47 +0800, lixiaokeng wrote:
> If one multipath device has two paths, the first is down (network
> failure) and the second is up, then we register a prkey to the
> device. The first path will register successfully but the second
> won't. Then fix the network. The uev_update_path will race with
> check_path. If uev_update_path -> pathinfo is called before
> check_path, the state of the first path will be set PATH_UP
> without checking persistent reservation registration.
> 
> Here we add checking in uev_update_path.
> 
> Signed-off-by: Lixiaokeng <lixiaokeng at huawei.com>
> ---
>  multipathd/main.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 2251e02c..0948bf81 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -1316,6 +1316,7 @@ uev_update_path (struct uevent *uev, struct
> vectors * vecs)
>         struct path * pp;
>         struct config *conf;
>         int needs_reinit = 0;
> +       int oldstate;
> 
>         switch ((rc = change_foreign(uev->udev))) {
>         case FOREIGN_OK:
> @@ -1366,9 +1367,22 @@ uev_update_path (struct uevent *uev, struct
> vectors * vecs)
>                         pp->udev = udev_device_ref(uev->udev);
>                         conf = get_multipath_config();
>                         pthread_cleanup_push(put_multipath_config,
> conf);
> +                       oldstate = pp->state;
> +
>                         if (pathinfo(pp, conf, DI_SYSFS|DI_NOIO) !=
> PATHINFO_OK)
>                                 condlog(1, "%s: pathinfo failed after
> change uevent",
>                                         uev->kernel);
> +
> +                       if (pp->state != oldstate && (pp->state ==
> PATH_UP || pp->state == PATH_GHOST)) {


I don't understand. pathinfo(DI_SYSFS|DI_NOIO) doesn't modify 
pp->state.  So your first condition should always be false.
Am I overlooking something?

Regards
Martin