From: Patrick McHardy <kaber@xxxxxxxxx> Add some helper functions for building the genmask as preparation for set transactions. Also add a little documentation how this stuff actually works. Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> --- include/net/netfilter/nf_tables.h | 28 ++++++++++++++++++++++++++++ net/netfilter/nf_tables_api.c | 17 ++++++----------- net/netfilter/nf_tables_core.c | 6 +----- 3 files changed, 35 insertions(+), 16 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index f190d26..4c46a32 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -720,6 +720,34 @@ void nft_unregister_expr(struct nft_expr_type *); #define MODULE_ALIAS_NFT_SET() \ MODULE_ALIAS("nft-set") +/* + * The gencursor defines two generations, the currently active and the + * next one. Objects contain a bitmask of 2 bits specifying the generations + * they're active in. A set bit means they're inactive in the generation + * represented by that bit. + * + * New objects start out as inactive in the current and active in the + * next generation. When committing the ruleset the bitmask is cleared, + * meaning they're active in all generations. When removing an object, + * it is set inactive in the next generation. After committing the ruleset, + * the objects are removed. + */ +static inline unsigned int nft_gencursor_next(const struct net *net) +{ + return net->nft.gencursor + 1 == 1 ? 1 : 0; +} + +static inline u8 nft_genmask_next(const struct net *net) +{ + return 1 << nft_gencursor_next(net); +} + +static inline u8 nft_genmask_cur(const struct net *net) +{ + /* Use ACCESS_ONCE() to prevent refetching the value for atomicity */ + return 1 << ACCESS_ONCE(net->nft.gencursor); +} + /** * struct nft_trans - nf_tables object update in transaction * diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index b35512f..66fa5e9 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -198,36 +198,31 @@ static int nft_delchain(struct nft_ctx *ctx) static inline bool nft_rule_is_active(struct net *net, const struct nft_rule *rule) { - return (rule->genmask & (1 << net->nft.gencursor)) == 0; -} - -static inline int gencursor_next(struct net *net) -{ - return net->nft.gencursor+1 == 1 ? 1 : 0; + return (rule->genmask & nft_genmask_cur(net)) == 0; } static inline int nft_rule_is_active_next(struct net *net, const struct nft_rule *rule) { - return (rule->genmask & (1 << gencursor_next(net))) == 0; + return (rule->genmask & nft_genmask_next(net)) == 0; } static inline void nft_rule_activate_next(struct net *net, struct nft_rule *rule) { /* Now inactive, will be active in the future */ - rule->genmask = (1 << net->nft.gencursor); + rule->genmask = nft_genmask_cur(net); } static inline void nft_rule_deactivate_next(struct net *net, struct nft_rule *rule) { - rule->genmask = (1 << gencursor_next(net)); + rule->genmask = nft_genmask_next(net); } static inline void nft_rule_clear(struct net *net, struct nft_rule *rule) { - rule->genmask &= ~(1 << gencursor_next(net)); + rule->genmask &= ~nft_genmask_next(net); } static int @@ -3626,7 +3621,7 @@ static int nf_tables_commit(struct sk_buff *skb) while (++net->nft.base_seq == 0); /* A new generation has just started */ - net->nft.gencursor = gencursor_next(net); + net->nft.gencursor = nft_gencursor_next(net); /* Make sure all packets have left the previous generation before * purging old rules. diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c index 4429008..ef4dfcb 100644 --- a/net/netfilter/nf_tables_core.c +++ b/net/netfilter/nf_tables_core.c @@ -121,11 +121,7 @@ nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops) struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE]; struct nft_stats *stats; int rulenum; - /* - * Cache cursor to avoid problems in case that the cursor is updated - * while traversing the ruleset. - */ - unsigned int gencursor = ACCESS_ONCE(net->nft.gencursor); + unsigned int gencursor = nft_genmask_cur(net); do_chain: rulenum = 0; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html