Re: [PATCH 06/17] batman-adv: replace call_rcu by kfree_rcu for simple kmem_cache_free callback
From: Sven Eckelmann <sven@narfation.org>
Date: 2024-10-14 07:13:24
Also in:
batman, kernel-janitors, lkml
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@inria.fr>
---
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.
Kind regards,
Sven
[1] https://lore.kernel.org/r/20240612133357.2596-1-linus.luessing@c0d3.blue (local)
quoted hunk ↗ jump to hunk
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); } /**
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