This is a note to let you know that I've just added the patch titled
netfilter: nft_set_rbtree: use read spinlock to avoid datapath contention
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nft_set_rbtree-use-read-spinlock-to-avoid-.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bceef0ad91672e1e05aad6926978a3e9e548d262
Author: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Date: Fri Sep 22 18:43:09 2023 +0200
netfilter: nft_set_rbtree: use read spinlock to avoid datapath contention
commit 96b33300fba880ec0eafcf3d82486f3463b4b6da upstream.
rbtree GC does not modify the datastructure, instead it collects expired
elements and it enqueues a GC transaction. Use a read spinlock instead
to avoid data contention while GC worker is running.
Fixes: f6c383b8c31a ("netfilter: nf_tables: adapt set backend to use GC transaction API")
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index f250b5399344a..70491ba98decb 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -622,8 +622,7 @@ static void nft_rbtree_gc(struct work_struct *work)
if (!gc)
goto done;
- write_lock_bh(&priv->lock);
- write_seqcount_begin(&priv->count);
+ read_lock_bh(&priv->lock);
for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) {
/* Ruleset has been updated, try later. */
@@ -673,8 +672,7 @@ static void nft_rbtree_gc(struct work_struct *work)
gc = nft_trans_gc_catchall(gc, gc_seq);
try_later:
- write_seqcount_end(&priv->count);
- write_unlock_bh(&priv->lock);
+ read_unlock_bh(&priv->lock);
if (gc)
nft_trans_gc_queue_async_done(gc);
