diff options
Diffstat (limited to 'include/net/netfilter')
| -rw-r--r-- | include/net/netfilter/nf_tables.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 6fd44959bf87..1ea13fcd388e 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -852,6 +852,41 @@ static inline void nft_set_elem_change_active(const struct nft_set *set, ext->genmask ^= nft_genmask_next(read_pnet(&set->pnet)); } +/* + * We use a free bit in the genmask field to indicate the element + * is busy, meaning it is currently being processed either by + * the netlink API or GC. + * + * Even though the genmask is only a single byte wide, this works + * because the extension structure if fully constant once initialized, + * so there are no non-atomic write accesses unless it is already + * marked busy. + */ +#define NFT_SET_ELEM_BUSY_MASK (1 << 2) + +#if defined(__LITTLE_ENDIAN_BITFIELD) +#define NFT_SET_ELEM_BUSY_BIT 2 +#elif defined(__BIG_ENDIAN_BITFIELD) +#define NFT_SET_ELEM_BUSY_BIT (BITS_PER_LONG - BITS_PER_BYTE + 2) +#else +#error +#endif + +static inline int nft_set_elem_mark_busy(struct nft_set_ext *ext) +{ + unsigned long *word = (unsigned long *)ext; + + BUILD_BUG_ON(offsetof(struct nft_set_ext, genmask) != 0); + return test_and_set_bit(NFT_SET_ELEM_BUSY_BIT, word); +} + +static inline void nft_set_elem_clear_busy(struct nft_set_ext *ext) +{ + unsigned long *word = (unsigned long *)ext; + + clear_bit(NFT_SET_ELEM_BUSY_BIT, word); +} + /** * struct nft_trans - nf_tables object update in transaction * |
