On Mon, 14 Oct 2024, Sven Eckelmann wrote:
> On Sunday, 13 October 2024 22:16:53 CEST Julia Lawall wrote:
> > Since SLOB was removed and since
> > commit 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"),
> > it is not necessary to use call_rcu when the callback only performs
> > kmem_cache_free. Use kfree_rcu() directly.
> >
> > The changes were made using Coccinelle.
> >
> > Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxxx>
> >
> > ---
> > net/batman-adv/translation-table.c | 47 ++-----------------------------------
> > 1 file changed, 3 insertions(+), 44 deletions(-)
>
>
> This was tried and we noticed that it is not safe [1]. So, I would get
> confirmation that commit 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier()
> from kmem_cache_destroy()") is fixing the problem which we had at that time.
> The commit message sounds like it but I just want to be sure.
Thanks for the feedback. I think that Vlastimil Babka can help with that.
julia
>
> Kind regards,
> Sven
>
> [1] https://lore.kernel.org/r/20240612133357.2596-1-linus.luessing@xxxxxxxxx
>
> >
> > diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
> > index 2243cec18ecc..b21ff3c36b07 100644
> > --- a/net/batman-adv/translation-table.c
> > +++ b/net/batman-adv/translation-table.c
> > @@ -208,20 +208,6 @@ batadv_tt_global_hash_find(struct batadv_priv *bat_priv, const u8 *addr,
> > return tt_global_entry;
> > }
> >
> > -/**
> > - * batadv_tt_local_entry_free_rcu() - free the tt_local_entry
> > - * @rcu: rcu pointer of the tt_local_entry
> > - */
> > -static void batadv_tt_local_entry_free_rcu(struct rcu_head *rcu)
> > -{
> > - struct batadv_tt_local_entry *tt_local_entry;
> > -
> > - tt_local_entry = container_of(rcu, struct batadv_tt_local_entry,
> > - common.rcu);
> > -
> > - kmem_cache_free(batadv_tl_cache, tt_local_entry);
> > -}
> > -
> > /**
> > * batadv_tt_local_entry_release() - release tt_local_entry from lists and queue
> > * for free after rcu grace period
> > @@ -236,7 +222,7 @@ static void batadv_tt_local_entry_release(struct kref *ref)
> >
> > batadv_softif_vlan_put(tt_local_entry->vlan);
> >
> > - call_rcu(&tt_local_entry->common.rcu, batadv_tt_local_entry_free_rcu);
> > + kfree_rcu(tt_local_entry, common.rcu);
> > }
> >
> > /**
> > @@ -254,20 +240,6 @@ batadv_tt_local_entry_put(struct batadv_tt_local_entry *tt_local_entry)
> > batadv_tt_local_entry_release);
> > }
> >
> > -/**
> > - * batadv_tt_global_entry_free_rcu() - free the tt_global_entry
> > - * @rcu: rcu pointer of the tt_global_entry
> > - */
> > -static void batadv_tt_global_entry_free_rcu(struct rcu_head *rcu)
> > -{
> > - struct batadv_tt_global_entry *tt_global_entry;
> > -
> > - tt_global_entry = container_of(rcu, struct batadv_tt_global_entry,
> > - common.rcu);
> > -
> > - kmem_cache_free(batadv_tg_cache, tt_global_entry);
> > -}
> > -
> > /**
> > * batadv_tt_global_entry_release() - release tt_global_entry from lists and
> > * queue for free after rcu grace period
> > @@ -282,7 +254,7 @@ void batadv_tt_global_entry_release(struct kref *ref)
> >
> > batadv_tt_global_del_orig_list(tt_global_entry);
> >
> > - call_rcu(&tt_global_entry->common.rcu, batadv_tt_global_entry_free_rcu);
> > + kfree_rcu(tt_global_entry, common.rcu);
> > }
> >
> > /**
> > @@ -407,19 +379,6 @@ static void batadv_tt_global_size_dec(struct batadv_orig_node *orig_node,
> > batadv_tt_global_size_mod(orig_node, vid, -1);
> > }
> >
> > -/**
> > - * batadv_tt_orig_list_entry_free_rcu() - free the orig_entry
> > - * @rcu: rcu pointer of the orig_entry
> > - */
> > -static void batadv_tt_orig_list_entry_free_rcu(struct rcu_head *rcu)
> > -{
> > - struct batadv_tt_orig_list_entry *orig_entry;
> > -
> > - orig_entry = container_of(rcu, struct batadv_tt_orig_list_entry, rcu);
> > -
> > - kmem_cache_free(batadv_tt_orig_cache, orig_entry);
> > -}
> > -
> > /**
> > * batadv_tt_orig_list_entry_release() - release tt orig entry from lists and
> > * queue for free after rcu grace period
> > @@ -433,7 +392,7 @@ static void batadv_tt_orig_list_entry_release(struct kref *ref)
> > refcount);
> >
> > batadv_orig_node_put(orig_entry->orig_node);
> > - call_rcu(&orig_entry->rcu, batadv_tt_orig_list_entry_free_rcu);
> > + kfree_rcu(orig_entry, rcu);
> > }
> >
> > /**
> >
> >
>
>
