Re: [PATCH v3 2/2] liveupdate: initialize incoming FLB state before finish

[Pasha Tatashin]

On Thu, Mar 26, 2026 at 12:26 AM Leo Timmins <leotimmins1974@xxxxxxxxx> wrote:
>
> luo_flb_file_finish_one() decremented incoming.count before making sure
> that the incoming FLB state had been materialized. If no earlier incoming
> retrieval had populated that state, the first decrement ran from zero and
> skipped the last-user finish path.
>
> Initialize the incoming FLB state before the first decrement so finish
> uses the serialized refcount instead of an uninitialized value.
>
> Fixes: cab056f2aae7 ("liveupdate: luo_flb: introduce File-Lifecycle-Bound global state")
> Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: Leo Timmins <leotimmins1974@xxxxxxxxx>
> ---
>  kernel/liveupdate/luo_flb.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/liveupdate/luo_flb.c b/kernel/liveupdate/luo_flb.c
> index f52e8114837e..855af655b09b 100644
> --- a/kernel/liveupdate/luo_flb.c
> +++ b/kernel/liveupdate/luo_flb.c
> @@ -192,10 +192,27 @@ static int luo_flb_retrieve_one(struct liveupdate_flb *flb)
>  static void luo_flb_file_finish_one(struct liveupdate_flb *flb)
>  {
>         struct luo_flb_private *private = luo_flb_get_private(flb);
> +       bool needs_retrieve = false;
>         u64 count;
>
> -       scoped_guard(mutex, &private->incoming.lock)
> +       scoped_guard(mutex, &private->incoming.lock) {
> +               if (!private->incoming.count && !private->incoming.finished)
> +                       needs_retrieve = true;
> +       }
> +
> +       if (needs_retrieve) {
> +               int err = luo_flb_retrieve_one(flb);
> +
> +               if (err) {
> +                       pr_warn("Failed to retrieve FLB '%s' during finish: %pe\n",
> +                               flb->compatible, ERR_PTR(err));
> +                       return;
> +               }
> +       }
> +
> +       scoped_guard(mutex, &private->incoming.lock) {
>                 count = --private->incoming.count;
> +       }

The braces are still added

>
>         if (!count) {
>                 struct liveupdate_flb_op_args args = {0};
> --
> 2.53.0
>