From 268eca112d919c6e9cd03be74f4deb5a91a945bc Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Tue, 9 Jun 2015 11:32:24 -0700 Subject: [PATCH] flow: Make assertions about offsets within struct flow easier to follow. Signed-off-by: Ben Pfaff Acked-by: Jarno Rajahalme --- lib/flow.c | 60 ++++++++++++++++++++++++++---------------------------- lib/util.h | 3 +++ 2 files changed, 32 insertions(+), 31 deletions(-) diff --git a/lib/flow.c b/lib/flow.c index d2dcc460e..3e99d5e6c 100644 --- a/lib/flow.c +++ b/lib/flow.c @@ -50,25 +50,32 @@ const uint8_t flow_segment_u64s[4] = { FLOW_U64S }; +/* Asserts that field 'f1' follows immediately after 'f0' in struct flow, + * without any intervening padding. */ +#define ASSERT_SEQUENTIAL(f0, f1) \ + BUILD_ASSERT_DECL(offsetof(struct flow, f0) \ + + MEMBER_SIZEOF(struct flow, f0) \ + == offsetof(struct flow, f1)) + +/* Asserts that fields 'f0' and 'f1' are in the same 32-bit aligned word within + * struct flow. */ +#define ASSERT_SAME_WORD(f0, f1) \ + BUILD_ASSERT_DECL(offsetof(struct flow, f0) / 4 \ + == offsetof(struct flow, f1) / 4) + +/* Asserts that 'f0' and 'f1' are both sequential and within the same 32-bit + * aligned word in struct flow. */ +#define ASSERT_SEQUENTIAL_SAME_WORD(f0, f1) \ + ASSERT_SEQUENTIAL(f0, f1); \ + ASSERT_SAME_WORD(f0, f1) + /* miniflow_extract() assumes the following to be true to optimize the * extraction process. */ -BUILD_ASSERT_DECL(offsetof(struct flow, dl_type) + 2 - == offsetof(struct flow, vlan_tci) && - offsetof(struct flow, dl_type) / 4 - == offsetof(struct flow, vlan_tci) / 4 ); - -BUILD_ASSERT_DECL(offsetof(struct flow, nw_frag) + 3 - == offsetof(struct flow, nw_proto) && - offsetof(struct flow, nw_tos) + 2 - == offsetof(struct flow, nw_proto) && - offsetof(struct flow, nw_ttl) + 1 - == offsetof(struct flow, nw_proto) && - offsetof(struct flow, nw_frag) / 4 - == offsetof(struct flow, nw_tos) / 4 && - offsetof(struct flow, nw_ttl) / 4 - == offsetof(struct flow, nw_tos) / 4 && - offsetof(struct flow, nw_proto) / 4 - == offsetof(struct flow, nw_tos) / 4); +ASSERT_SEQUENTIAL_SAME_WORD(dl_type, vlan_tci); + +ASSERT_SEQUENTIAL_SAME_WORD(nw_frag, nw_tos); +ASSERT_SEQUENTIAL_SAME_WORD(nw_tos, nw_ttl); +ASSERT_SEQUENTIAL_SAME_WORD(nw_ttl, nw_proto); /* TCP flags in the middle of a BE64, zeroes in the other half. */ BUILD_ASSERT_DECL(offsetof(struct flow, tcp_flags) % 8 == 4); @@ -80,10 +87,7 @@ BUILD_ASSERT_DECL(offsetof(struct flow, tcp_flags) % 8 == 4); #define TCP_FLAGS_BE32(tcp_ctl) ((OVS_FORCE ovs_be32)TCP_FLAGS_BE16(tcp_ctl)) #endif -BUILD_ASSERT_DECL(offsetof(struct flow, tp_src) + 2 - == offsetof(struct flow, tp_dst) && - offsetof(struct flow, tp_src) / 4 - == offsetof(struct flow, tp_dst) / 4); +ASSERT_SEQUENTIAL_SAME_WORD(tp_src, tp_dst); /* Removes 'size' bytes from the head end of '*datap', of size '*sizep', which * must contain at least 'size' bytes of data. Returns the first byte of data @@ -458,8 +462,7 @@ miniflow_extract(struct dp_packet *packet, struct miniflow *dst) ovs_be16 vlan_tci; /* Link layer. */ - BUILD_ASSERT(offsetof(struct flow, dl_dst) + 6 - == offsetof(struct flow, dl_src)); + ASSERT_SEQUENTIAL(dl_dst, dl_src); miniflow_push_macs(mf, dl_dst, data); /* dl_type, vlan_tci. */ vlan_tci = parse_vlan(&data, &size); @@ -645,8 +648,7 @@ miniflow_extract(struct dp_packet *packet, struct miniflow *dst) } /* Must be adjacent. */ - BUILD_ASSERT(offsetof(struct flow, arp_sha) + 6 - == offsetof(struct flow, arp_tha)); + ASSERT_SEQUENTIAL(arp_sha, arp_tha); memcpy(arp_buf[0], arp->ar_sha, ETH_ADDR_LEN); memcpy(arp_buf[1], arp->ar_tha, ETH_ADDR_LEN); @@ -1252,12 +1254,8 @@ miniflow_hash_5tuple(const struct miniflow *flow, uint32_t basis) return hash; } -BUILD_ASSERT_DECL(offsetof(struct flow, tp_src) + 2 - == offsetof(struct flow, tp_dst) && - offsetof(struct flow, tp_src) / 4 - == offsetof(struct flow, tp_dst) / 4); -BUILD_ASSERT_DECL(offsetof(struct flow, ipv6_src) + 16 - == offsetof(struct flow, ipv6_dst)); +ASSERT_SEQUENTIAL_SAME_WORD(tp_src, tp_dst); +ASSERT_SEQUENTIAL(ipv6_src, ipv6_dst); /* Calculates the 5-tuple hash from the given flow. */ uint32_t diff --git a/lib/util.h b/lib/util.h index 59276e357..0d1e727ed 100644 --- a/lib/util.h +++ b/lib/util.h @@ -199,6 +199,9 @@ ovs_prefetch_range(const void *start, size_t size) ((char *) &(OBJECT)->MEMBER - (char *) (OBJECT)) #endif +/* Yields the size of MEMBER within STRUCT. */ +#define MEMBER_SIZEOF(STRUCT, MEMBER) (sizeof(((STRUCT *) NULL)->MEMBER)) + /* Given POINTER, the address of the given MEMBER in a STRUCT object, returns the STRUCT object. */ #define CONTAINER_OF(POINTER, STRUCT, MEMBER) \ -- 2.20.1