From d88919772fc833193a5962d2f482993c3e040421 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Wed, 23 Aug 2023 11:49:34 +0200 Subject: [PATCH -stable,4.14 15/17] netfilter: nf_tables: defer gc run if previous batch is still pending commit 8e51830e29e12670b4c10df070a4ea4c9593e961 upstream. Don't queue more gc work, else we may queue the same elements multiple times. If an element is flagged as dead, this can mean that either the previous gc request was invalidated/discarded by a transaction or that the previous request is still pending in the system work queue. The latter will happen if the gc interval is set to a very low value, e.g. 1ms, and system work queue is backlogged. The sets refcount is 1 if no previous gc requeusts are queued, so add a helper for this and skip gc run if old requests are pending. Add a helper for this and skip the gc run in this case. Fixes: f6c383b8c31a ("netfilter: nf_tables: adapt set backend to use GC transaction API") Signed-off-by: Florian Westphal --- include/net/netfilter/nf_tables.h | 5 +++++ net/netfilter/nft_set_hash.c | 3 +++ 2 files changed, 8 insertions(+) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index bb24b7d058d9..702e968613ab 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -440,6 +440,11 @@ static inline void *nft_set_priv(const struct nft_set *set) return (void *)set->data; } +static inline bool nft_set_gc_is_pending(const struct nft_set *s) +{ + return refcount_read(&s->refs) != 1; +} + static inline struct nft_set *nft_set_container_of(const void *priv) { return (void *)priv - offsetof(struct nft_set, data); diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c index aa226c494258..68c8fe094325 100644 --- a/net/netfilter/nft_set_hash.c +++ b/net/netfilter/nft_set_hash.c @@ -288,6 +288,9 @@ static void nft_rhash_gc(struct work_struct *work) net = read_pnet(&set->net); gc_seq = READ_ONCE(net->nft.gc_seq); + if (nft_set_gc_is_pending(set)) + goto done; + gc = nft_trans_gc_alloc(set, gc_seq, GFP_KERNEL); if (!gc) goto done; -- 2.30.2