> -----Original Message-----
> From: Su Sai <susai.ss at bytedance.com>
> Sent: Friday 1 August 2025 16:29
> To: dev at dpdk.org
> Cc: jasvinder.singh at intel.com; thomas at monjalon.net; Marat Khalili
> <marat.khalili at huawei.com>; Su Sai <susai.ss at bytedance.com>
> Subject: [v2] net/cksum: compute raw cksum for several segments
>
> 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 <susai.ss at bytedance.com>
> ---
> .mailmap | 1 +
> app/test/test_cksum.c | 104
> ++++++++++++++++++++++++++++++++++++++++++
> lib/net/rte_cksum.h | 26 +++++++++--
> 3 files changed, 128 insertions(+), 3 deletions(-)
>
> diff --git a/.mailmap b/.mailmap
> index 34a99f93a1..838b544a97 100644
> --- a/.mailmap
> +++ b/.mailmap
> @@ -1891,3 +1891,4 @@ Zoltan Kiss <zoltan.kiss at schaman.hu>
> <zoltan.kiss at linaro.org>
> Zorik Machulsky <zorik at amazon.com>
> Zyta Szpak <zyta at marvell.com> <zr at semihalf.com>
> Zyta Szpak <zyta at marvell.com> <zyta.szpak at semihalf.com>
> +Su Sai <susai.ss at bytedance.com>
> diff --git a/app/test/test_cksum.c b/app/test/test_cksum.c
> index f2ab5af5a7..d2435a9962 100644
> --- a/app/test/test_cksum.c
> +++ b/app/test/test_cksum.c
> @@ -85,6 +85,39 @@ 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 lenght 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 +256,71 @@ 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;
> + void *l3_hdr;
> + uint32_t l3;
> + 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]);
> + 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]);
> +
> + return 0;
> +
> +fail:
> + for (i = 0; i < segs_len; i++) {
> + if (m[i])
> + rte_pktmbuf_free(m[i]);
> + }
> +
> + return -1;
> +}
> +
> static int
> test_cksum(void)
> {
> @@ -256,6 +354,12 @@ 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..aa584d5f8d 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 +138,9 @@ 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 tmp;
> uint32_t seglen, done;
> + uint64_t sum;
>
> /* easy case: all data in the first segment */
> if (off + len <= rte_pktmbuf_data_len(m)) {
> @@ -157,7 +177,7 @@ 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 +189,7 @@ 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;
> }
>
> --
> 2.39.2 (Apple Git-143)
Hi, thanks a lot for providing a test. Note that something is garbling your patches: wrapping long lines etc.
For the attached ungarbled version:
Reviewed-by: Marat Khalili <marat.khalili at huawei.com>
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