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[net,2/3] netfilter: nft_counter: Synchronize nft_counter_reset() against reader.

Message ID 20240822101842.4234-3-pablo@netfilter.org (mailing list archive)
State Accepted
Commit a0b39e2dc7017ac667b70bdeee5293e410fab2fb
Delegated to: Netdev Maintainers
Headers show
Series [net,1/3] netfilter: nft_counter: Disable BH in nft_counter_offload_stats(). | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 16 this patch: 16
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 2 maintainers not CCed: coreteam@netfilter.org kadlec@netfilter.org
netdev/build_clang success Errors and warnings before: 16 this patch: 16
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 16 this patch: 16
netdev/checkpatch warning WARNING: Please use correct Fixes: style 'Fixes: <12 chars of sha1> ("<title line>")' - ie: 'Fixes: d84701ecbcd6 ("netfilter: nft_counter: rework atomic dump and reset")'
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest warning net-next-2024-08-22--18-00 (tests: 711)

Commit Message

Pablo Neira Ayuso Aug. 22, 2024, 10:18 a.m. UTC 
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

nft_counter_reset() resets the counter by subtracting the previously
retrieved value from the counter. This is a write operation on the
counter and as such it requires to be performed with a write sequence of
nft_counter_seq to serialize against its possible reader.

Update the packets/ bytes within write-sequence of nft_counter_seq.

Fixes: d84701ecbcd6a ("netfilter: nft_counter: rework atomic dump and reset")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_counter.c | 5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c
index 16f40b503d37..eab0dc66bee6 100644
--- a/net/netfilter/nft_counter.c
+++ b/net/netfilter/nft_counter.c
@@ -107,11 +107,16 @@  static void nft_counter_reset(struct nft_counter_percpu_priv *priv,
 			      struct nft_counter *total)
 {
 	struct nft_counter *this_cpu;
+	seqcount_t *myseq;
 
 	local_bh_disable();
 	this_cpu = this_cpu_ptr(priv->counter);
+	myseq = this_cpu_ptr(&nft_counter_seq);
+
+	write_seqcount_begin(myseq);
 	this_cpu->packets -= total->packets;
 	this_cpu->bytes -= total->bytes;
+	write_seqcount_end(myseq);
 	local_bh_enable();
 }