From: Florian Westphal fw@strlen.de
commit 2f941622fd88328ca75806c45c9e9709286a0609 upstream.
WARNING: CPU: 1 PID: 16059 at lib/refcount.c:31 refcount_warn_saturate+0xdf/0xf [..] __nft_mt_tg_destroy+0x42/0x50 [nft_compat] nft_target_destroy+0x63/0x80 [nft_compat] nf_tables_expr_destroy+0x1b/0x30 [nf_tables] nf_tables_rule_destroy+0x3a/0x70 [nf_tables] nf_tables_exit_net+0x186/0x3d0 [nf_tables]
Happens when a compat expr is destoyed from abort path. There is no functional impact; after this work queue is flushed unconditionally if its pending.
This removes the waitcount optimization. Test of repeated iptables-restore of a ~60k kubernetes ruleset doesn't indicate a slowdown. In case the counter is needed after all for some workloads we can revert this and increment the refcount for the != NFT_PREPARE_TRANS case to avoid the increment/decrement imbalance.
While at it, also flush for match case, this was an oversight in the original patch.
Fixes: ffe8923f109b7e ("netfilter: nft_compat: make sure xtables destructors have run") Reported-by: kernel test robot rong.a.chen@intel.com Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netfilter/nft_compat.c | 37 ++++++++++++++----------------------- 1 file changed, 14 insertions(+), 23 deletions(-)
--- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -27,8 +27,6 @@ struct nft_xt_match_priv { void *info; };
-static refcount_t nft_compat_pending_destroy = REFCOUNT_INIT(1); - static int nft_compat_chain_validate_dependency(const struct nft_ctx *ctx, const char *tablename) { @@ -215,6 +213,17 @@ static int nft_parse_compat(const struct return 0; }
+static void nft_compat_wait_for_destructors(void) +{ + /* xtables matches or targets can have side effects, e.g. + * creation/destruction of /proc files. + * The xt ->destroy functions are run asynchronously from + * work queue. If we have pending invocations we thus + * need to wait for those to finish. + */ + nf_tables_trans_destroy_flush_work(); +} + static int nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) @@ -238,14 +247,7 @@ nft_target_init(const struct nft_ctx *ct
nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
- /* xtables matches or targets can have side effects, e.g. - * creation/destruction of /proc files. - * The xt ->destroy functions are run asynchronously from - * work queue. If we have pending invocations we thus - * need to wait for those to finish. - */ - if (refcount_read(&nft_compat_pending_destroy) > 1) - nf_tables_trans_destroy_flush_work(); + nft_compat_wait_for_destructors();
ret = xt_check_target(&par, size, proto, inv); if (ret < 0) @@ -260,7 +262,6 @@ nft_target_init(const struct nft_ctx *ct
static void __nft_mt_tg_destroy(struct module *me, const struct nft_expr *expr) { - refcount_dec(&nft_compat_pending_destroy); module_put(me); kfree(expr->ops); } @@ -468,6 +469,8 @@ __nft_match_init(const struct nft_ctx *c
nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
+ nft_compat_wait_for_destructors(); + return xt_check_match(&par, size, proto, inv); }
@@ -716,14 +719,6 @@ static const struct nfnetlink_subsystem
static struct nft_expr_type nft_match_type;
-static void nft_mt_tg_deactivate(const struct nft_ctx *ctx, - const struct nft_expr *expr, - enum nft_trans_phase phase) -{ - if (phase == NFT_TRANS_COMMIT) - refcount_inc(&nft_compat_pending_destroy); -} - static const struct nft_expr_ops * nft_match_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[]) @@ -762,7 +757,6 @@ nft_match_select_ops(const struct nft_ct ops->type = &nft_match_type; ops->eval = nft_match_eval; ops->init = nft_match_init; - ops->deactivate = nft_mt_tg_deactivate, ops->destroy = nft_match_destroy; ops->dump = nft_match_dump; ops->validate = nft_match_validate; @@ -853,7 +847,6 @@ nft_target_select_ops(const struct nft_c ops->size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize)); ops->init = nft_target_init; ops->destroy = nft_target_destroy; - ops->deactivate = nft_mt_tg_deactivate, ops->dump = nft_target_dump; ops->validate = nft_target_validate; ops->data = target; @@ -917,8 +910,6 @@ static void __exit nft_compat_module_exi nfnetlink_subsys_unregister(&nfnl_compat_subsys); nft_unregister_expr(&nft_target_type); nft_unregister_expr(&nft_match_type); - - WARN_ON_ONCE(refcount_read(&nft_compat_pending_destroy) != 1); }
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);