On Fri, 9 Sept 2022 at 07:27, Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 9/4/22 1:41 PM, Kumar Kartikeya Dwivedi wrote:
> > diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h
> > index 7ea18d4da84b..6786d00f004e 100644
> > --- a/include/linux/bpf_local_storage.h
> > +++ b/include/linux/bpf_local_storage.h
> > @@ -74,7 +74,7 @@ struct bpf_local_storage_elem {
> > struct hlist_node snode; /* Linked to bpf_local_storage */
> > struct bpf_local_storage __rcu *local_storage;
> > struct rcu_head rcu;
> > - /* 8 bytes hole */
> > + struct bpf_map *map; /* Only set for bpf_selem_free_rcu */
>
> Instead of adding another map ptr and using the last 8 bytes hole,
>
> > /* The data is stored in another cacheline to minimize
> > * the number of cachelines access during a cache hit.
> > */
> > diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
> > index 802fc15b0d73..4a725379d761 100644
> > --- a/kernel/bpf/bpf_local_storage.c
> > +++ b/kernel/bpf/bpf_local_storage.c
> > @@ -74,7 +74,8 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
> > gfp_flags | __GFP_NOWARN);
> > if (selem) {
> > if (value)
> > - memcpy(SDATA(selem)->data, value, smap->map.value_size);
> > + copy_map_value(&smap->map, SDATA(selem)->data, value);
> > + /* No call to check_and_init_map_value as memory is zero init */
> > return selem;
> > }
> >
> > @@ -92,12 +93,27 @@ void bpf_local_storage_free_rcu(struct rcu_head *rcu)
> > kfree_rcu(local_storage, rcu);
> > }
> >
> > +static void check_and_free_fields(struct bpf_local_storage_elem *selem)
> > +{
> > + if (map_value_has_kptrs(selem->map))
>
> could SDATA(selem)->smap->map be used here ?
>
Yeah, that should work. Thanks Martin.
> > + bpf_map_free_kptrs(selem->map, SDATA(selem));
> > +}
> > +
> [...]
