<div dir="ltr">Hi Stephen, I've revised the patch per your feedback and sent out v4: net/cksum: compute raw cksum for several segments. Your review is appreciated.</div> <div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Tue, Jun 9, 2026 at 1:02 AM Stephen Hemminger <<a href="mailto:stephen@networkplumber.org">stephen@networkplumber.org</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Mon, 4 Aug 2025 11:54:30 +0800 Su Sai <<a href="mailto:spiderdetective.ss@gmail.com" target="_blank">spiderdetective.ss@gmail.com</a>> wrote: > The rte_raw_cksum_mbuf function is used to compute > the raw checksum of a packet. > If the packet payload stored in multi mbuf, the function > will goto the hard case. In hard case, > the variable 'tmp' is a type of uint32_t, > so rte_bswap16 will drop high 16 bit. > Meanwhile, the variable 'sum' is a type of uint32_t, > so 'sum += tmp' will drop the carry when overflow. > Both drop will make cksum incorrect. > This commit fixes the above bug. > > Signed-off-by: Su Sai <<a href="mailto:spiderdetective.ss@gmail.com" target="_blank">spiderdetective.ss@gmail.com</a>> > --- > .mailmap | 1 + > app/test/test_cksum.c | 106 ++++++++++++++++++++++++++++++++++++++++++ > lib/net/rte_cksum.h | 27 +++++++++-- > 3 files changed, 130 insertions(+), 4 deletions(-) > > diff --git a/.mailmap b/.mailmap > index 34a99f93a1..1da1d9f8e1 100644 > --- a/.mailmap > +++ b/.mailmap > @@ -1552,6 +1552,7 @@ Sunil Kumar Kori <<a href="mailto:skori@marvell.com" target="_blank">skori@marvell.com</a>> <<a href="mailto:sunil.kori@nxp.com" target="_blank">sunil.kori@nxp.com</a>> > Sunil Pai G <<a href="mailto:sunil.pai.g@intel.com" target="_blank">sunil.pai.g@intel.com</a>> > Sunil Uttarwar <<a href="mailto:sunilprakashrao.uttarwar@amd.com" target="_blank">sunilprakashrao.uttarwar@amd.com</a>> > Sun Jiajia <<a href="mailto:sunx.jiajia@intel.com" target="_blank">sunx.jiajia@intel.com</a>> > +Su Sai <<a href="mailto:spiderdetective.ss@gmail.com" target="_blank">spiderdetective.ss@gmail.com</a>> <<a href="mailto:susai.ss@bytedance.com" target="_blank">susai.ss@bytedance.com</a>> > Sunyang Wu <<a href="mailto:sunyang.wu@jaguarmicro.com" target="_blank">sunyang.wu@jaguarmicro.com</a>> > Surabhi Boob <<a href="mailto:surabhi.boob@intel.com" target="_blank">surabhi.boob@intel.com</a>> > Suyang Ju <<a href="mailto:sju@paloaltonetworks.com" target="_blank">sju@paloaltonetworks.com</a>> > diff --git a/app/test/test_cksum.c b/app/test/test_cksum.c > index f2ab5af5a7..fb2e3cf9e6 100644 > --- a/app/test/test_cksum.c > +++ b/app/test/test_cksum.c > @@ -85,6 +85,42 @@ static const char test_cksum_ipv4_opts_udp[] = { > 0x00, 0x35, 0x00, 0x09, 0x89, 0x6f, 0x78, > }; > > +/* > + * generated in scapy with > + * Ether()/IP()/TCP(options=[NOP,NOP,Timestamps])/os.urandom(113)) > + */ > +static const char test_cksum_ipv4_tcp_multi_segs[] = { > + 0x00, 0x16, 0x3e, 0x0b, 0x6b, 0xd2, 0xee, 0xff, > + 0xff, 0xff, 0xff, 0xff, 0x08, 0x00, 0x45, 0x00, > + 0x00, 0xa5, 0x46, 0x10, 0x40, 0x00, 0x40, 0x06, > + 0x80, 0xb5, 0xc0, 0xa8, 0xf9, 0x1d, 0xc0, 0xa8, > + 0xf9, 0x1e, 0xdc, 0xa2, 0x14, 0x51, 0xbb, 0x8f, > + 0xa0, 0x00, 0xe4, 0x7c, 0xe4, 0xb8, 0x80, 0x10, > + 0x02, 0x00, 0x4b, 0xc1, 0x00, 0x00, 0x01, 0x01, > + 0x08, 0x0a, 0x90, 0x60, 0xf4, 0xff, 0x03, 0xc5, > + 0xb4, 0x19, 0x77, 0x34, 0xd4, 0xdc, 0x84, 0x86, > + 0xff, 0x44, 0x09, 0x63, 0x36, 0x2e, 0x26, 0x9b, > + 0x90, 0x70, 0xf2, 0xed, 0xc8, 0x5b, 0x87, 0xaa, > + 0xb4, 0x67, 0x6b, 0x32, 0x3d, 0xc4, 0xbf, 0x15, > + 0xa9, 0x16, 0x6c, 0x2a, 0x9d, 0xb2, 0xb7, 0x6b, > + 0x58, 0x44, 0x58, 0x12, 0x4b, 0x8f, 0xe5, 0x12, > + 0x11, 0x90, 0x94, 0x68, 0x37, 0xad, 0x0a, 0x9b, > + 0xd6, 0x79, 0xf2, 0xb7, 0x31, 0xcf, 0x44, 0x22, > + 0xc8, 0x99, 0x3f, 0xe5, 0xe7, 0xac, 0xc7, 0x0b, > + 0x86, 0xdf, 0xda, 0xed, 0x0a, 0x0f, 0x86, 0xd7, > + 0x48, 0xe2, 0xf1, 0xc2, 0x43, 0xed, 0x47, 0x3a, > + 0xea, 0x25, 0x2d, 0xd6, 0x60, 0x38, 0x30, 0x07, > + 0x28, 0xdd, 0x1f, 0x0c, 0xdd, 0x7b, 0x7c, 0xd9, > + 0x35, 0x9d, 0x14, 0xaa, 0xc6, 0x35, 0xd1, 0x03, > + 0x38, 0xb1, 0xf5, > +}; > + > +static const uint8_t test_cksum_ipv4_tcp_multi_segs_len[] = { > + 66, /* the first seg contains all headers, including L2 to L4 */ > + 61, /* the second seg length is odd, test byte order independent */ > + 52, /* three segs are sufficient to test the most complex scenarios */ > +}; > + > /* test l3/l4 checksum api */ > static int > test_l4_cksum(struct rte_mempool *pktmbuf_pool, const char *pktdata, size_t len) > @@ -223,6 +259,70 @@ test_l4_cksum(struct rte_mempool *pktmbuf_pool, const char *pktdata, size_t len) > return -1; > } > > +/* test l4 checksum api for a packet with multiple mbufs */ > +static int > +test_l4_cksum_multi_mbufs(struct rte_mempool *pktmbuf_pool, const char *pktdata, size_t len, > + const uint8_t *segs, size_t segs_len) > +{ > + struct rte_mbuf *m[NB_MBUF] = {0}; > + struct rte_mbuf *m_hdr = NULL; > + struct rte_net_hdr_lens hdr_lens; > + size_t i, off = 0; > + uint32_t packet_type, l3; > + void *l3_hdr; > + char *data; > + > + for (i = 0; i < segs_len; i++) { > + m[i] = rte_pktmbuf_alloc(pktmbuf_pool); > + if (m[i] == NULL) > + GOTO_FAIL("Cannot allocate mbuf"); > + > + data = rte_pktmbuf_append(m[i], segs[i]); > + if (data == NULL) > + GOTO_FAIL("Cannot append data"); > + > + rte_memcpy(data, pktdata + off, segs[i]); Tests (except rte_memcpy test) should not use rte_memcpy, instead use regular memcpy which has better coverage from analyzers. > + off += segs[i]; > + > + if (m_hdr) { > + if (rte_pktmbuf_chain(m_hdr, m[i])) > + GOTO_FAIL("Cannot chain mbuf"); > + } else { > + m_hdr = m[i]; > + } > + } > + > + if (off != len) > + GOTO_FAIL("Invalid segs"); > + > + packet_type = rte_net_get_ptype(m_hdr, &hdr_lens, RTE_PTYPE_ALL_MASK); > + l3 = packet_type & RTE_PTYPE_L3_MASK; > + > + l3_hdr = rte_pktmbuf_mtod_offset(m_hdr, void *, hdr_lens.l2_len); > + off = hdr_lens.l2_len + hdr_lens.l3_len; > + > + if (l3 == RTE_PTYPE_L3_IPV4 || l3 == RTE_PTYPE_L3_IPV4_EXT) { > + if (rte_ipv4_udptcp_cksum_mbuf_verify(m_hdr, l3_hdr, off) != 0) > + GOTO_FAIL("Invalid L4 checksum verification for multiple mbufs"); > + } else if (l3 == RTE_PTYPE_L3_IPV6 || l3 == RTE_PTYPE_L3_IPV6_EXT) { > + if (rte_ipv6_udptcp_cksum_mbuf_verify(m_hdr, l3_hdr, off) != 0) > + GOTO_FAIL("Invalid L4 checksum verification for multiple mbufs"); > + } > + > + for (i = 0; i < segs_len; i++) > + rte_pktmbuf_free(m[i]); Can avoid the loop here and elsewhere by using rte_pktmbuf_free_bulk() > + return 0; > + > +fail: > + for (i = 0; i < segs_len; i++) { > + if (m[i]) > + rte_pktmbuf_free(m[i]); > + } Freebulk will work here > + return -1; > +} > + > static int > test_cksum(void) > { > @@ -256,6 +356,12 @@ test_cksum(void) > sizeof(test_cksum_ipv4_opts_udp)) < 0) > GOTO_FAIL("checksum error on ipv4_opts_udp"); > > + if (test_l4_cksum_multi_mbufs(pktmbuf_pool, test_cksum_ipv4_tcp_multi_segs, > + sizeof(test_cksum_ipv4_tcp_multi_segs), > + test_cksum_ipv4_tcp_multi_segs_len, > + sizeof(test_cksum_ipv4_tcp_multi_segs_len)) < 0) > + GOTO_FAIL("checksum error on multi mbufs check"); > + > rte_mempool_free(pktmbuf_pool); > > return 0; > diff --git a/lib/net/rte_cksum.h b/lib/net/rte_cksum.h > index a8e8927952..679ba82eb6 100644 > --- a/lib/net/rte_cksum.h > +++ b/lib/net/rte_cksum.h > @@ -80,6 +80,25 @@ __rte_raw_cksum_reduce(uint32_t sum) > return (uint16_t)sum; > } > > +/** > + * @internal Reduce a sum to the non-complemented checksum. > + * Helper routine for the rte_raw_cksum_mbuf(). > + * > + * @param sum > + * Value of the sum. > + * @return > + * The non-complemented checksum. > + */ > +static inline uint16_t > +__rte_raw_cksum_reduce_u64(uint64_t sum) > +{ > + uint32_t tmp; > + > + tmp = __rte_raw_cksum_reduce((uint32_t)sum); > + tmp += __rte_raw_cksum_reduce((uint32_t)(sum >> 32)); > + return __rte_raw_cksum_reduce(tmp); > +} > + > /** > * Process the non-complemented checksum of a buffer. > * > @@ -119,8 +138,8 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len, > { > const struct rte_mbuf *seg; > const char *buf; > - uint32_t sum, tmp; > - uint32_t seglen, done; > + uint32_t seglen, done, tmp; > + uint64_t sum; > > /* easy case: all data in the first segment */ > if (off + len <= rte_pktmbuf_data_len(m)) { > @@ -157,7 +176,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len, > for (;;) { > tmp = __rte_raw_cksum(buf, seglen, 0); > if (done & 1) > - tmp = rte_bswap16((uint16_t)tmp); > + tmp = rte_bswap32(tmp); > sum += tmp; > done += seglen; > if (done == len) > @@ -169,7 +188,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len, > seglen = len - done; > } > > - *cksum = __rte_raw_cksum_reduce(sum); > + *cksum = __rte_raw_cksum_reduce_u64(sum); > return 0; > } > </blockquote></div>