From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 45/47] netfilter: x_tables: Add note about how to free percpu counters
Date: Fri, 30 Mar 2018 13:46:17 +0200 [thread overview]
Message-ID: <20180330114619.18797-6-pablo@netfilter.org> (raw)
In-Reply-To: <20180330114619.18797-1-pablo@netfilter.org>
From: Ben Hutchings <ben.hutchings@codethink.co.uk>
Due to the way percpu counters are allocated and freed in blocks,
it is not safe to free counters individually. Currently all callers
do the right thing, but let's note this restriction.
Fixes: ae0ac0ed6fcf ("netfilter: x_tables: pack percpu counter allocations")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/x_tables.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index bac932f1c582..75cd5196b29b 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1854,7 +1854,9 @@ EXPORT_SYMBOL_GPL(xt_proto_fini);
* to fetch the real percpu counter.
*
* To speed up allocation and improve data locality, a 4kb block is
- * allocated.
+ * allocated. Freeing any counter may free an entire block, so all
+ * counters allocated using the same state must be freed at the same
+ * time.
*
* xt_percpu_counter_alloc_state contains the base address of the
* allocated page and the current sub-offset.
--
2.11.0
next prev parent reply other threads:[~2018-03-30 11:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-30 11:46 [PATCH 40/47] netfilter: nf_tables: build-in filter chain type Pablo Neira Ayuso
2018-03-30 11:46 ` [PATCH 41/47] netfilter: nf_tables: enable conntrack if NAT chain is registered Pablo Neira Ayuso
2018-03-30 11:46 ` [PATCH 42/47] netfilter: nf_tables: rename to nft_set_lookup_global() Pablo Neira Ayuso
2018-03-30 11:46 ` [PATCH 43/47] netfilter: nf_tables: use nft_set_lookup_global from nf_tables_newsetelem() Pablo Neira Ayuso
2018-03-30 11:46 ` [PATCH 44/47] netfilter: Merge assignment with return Pablo Neira Ayuso
2018-03-30 11:46 ` Pablo Neira Ayuso [this message]
2018-03-30 11:46 ` [PATCH 46/47] Revert "netfilter: x_tables: ensure last rule in base chain matches underflow/policy" Pablo Neira Ayuso
2018-03-30 11:46 ` [PATCH 47/47] netfilter: ipset: Use is_zero_ether_addr instead of static and memcmp Pablo Neira Ayuso
2018-04-04 15:38 ` [PATCH 40/47] netfilter: nf_tables: build-in filter chain type Arnd Bergmann
2018-04-04 15:46 ` Pablo Neira Ayuso
2018-04-04 15:50 ` Arnd Bergmann
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