RE: [PATCH net-next 04/10] RDMA/siw: use skb_crc32c() instead of __skb_checksum()

Bernard Metzler
2025-05-19T09:04:34Z

> -----Original Message-----
> From: Eric Biggers <ebiggers@kernel.org>
> Sent: Sunday, May 11, 2025 2:41 AM
> To: netdev@vger.kernel.org
> Cc: linux-nvme@lists.infradead.org; linux-sctp@vger.kernel.org; linux-
> rdma@vger.kernel.org; linux-kernel@vger.kernel.org; Daniel Borkmann
> <daniel@iogearbox.net>; Marcelo Ricardo Leitner
> <marcelo.leitner@gmail.com>; Sagi Grimberg <sagi@grimberg.me>; Ard
> Biesheuvel <ardb@kernel.org>
> Subject: [EXTERNAL] [PATCH net-next 04/10] RDMA/siw: use skb_crc32c()
> instead of __skb_checksum()
>
> From: Eric Biggers <ebiggers@google.com>
>
> Instead of calling __skb_checksum() with a skb_checksum_ops struct that
> does CRC32C, just call the new function skb_crc32c(). This is faster
> and simpler.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> drivers/infiniband/sw/siw/Kconfig | 1 +
> drivers/infiniband/sw/siw/siw.h | 22 +---------------------
> 2 files changed, 2 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/infiniband/sw/siw/Kconfig
> b/drivers/infiniband/sw/siw/Kconfig
> index ae4a953e2a03..186f182b80e7 100644
> --- a/drivers/infiniband/sw/siw/Kconfig
> +++ b/drivers/infiniband/sw/siw/Kconfig
> @@ -1,10 +1,11 @@
> config RDMA_SIW
> tristate "Software RDMA over TCP/IP (iWARP) driver"
> depends on INET && INFINIBAND
> depends on INFINIBAND_VIRT_DMA
> select CRC32
> + select NET_CRC32C
> help
> This driver implements the iWARP RDMA transport over
> the Linux TCP/IP network stack. It enables a system with a
> standard Ethernet adapter to interoperate with a iWARP
> adapter or with another system running the SIW driver.
> diff --git a/drivers/infiniband/sw/siw/siw.h
> b/drivers/infiniband/sw/siw/siw.h
> index 385067e07faf..d9e5a2e4c471 100644
> --- a/drivers/infiniband/sw/siw/siw.h
> +++ b/drivers/infiniband/sw/siw/siw.h
> @@ -691,33 +691,13 @@ static inline void siw_crc_oneshot(const void *data,
> size_t len, u8 out[4])
> siw_crc_init(&crc);
> siw_crc_update(&crc, data, len);
> return siw_crc_final(&crc, out);
> }
>
> -static inline __wsum siw_csum_update(const void *buff, int len, __wsum
> sum)
> -{
> - return (__force __wsum)crc32c((__force __u32)sum, buff, len);
> -}
> -
> -static inline __wsum siw_csum_combine(__wsum csum, __wsum csum2, int
> offset,
> - int len)
> -{
> - return (__force __wsum)crc32c_combine((__force __u32)csum,
> - (__force __u32)csum2, len);
> -}
> -
> static inline void siw_crc_skb(struct siw_rx_stream *srx, unsigned int
> len)
> {
> - const struct skb_checksum_ops siw_cs_ops = {
> - .update = siw_csum_update,
> - .combine = siw_csum_combine,
> - };
> - __wsum crc = (__force __wsum)srx->mpa_crc;
> -
> - crc = __skb_checksum(srx->skb, srx->skb_offset, len, crc,
> - &siw_cs_ops);
> - srx->mpa_crc = (__force u32)crc;
> + srx->mpa_crc = skb_crc32c(srx->skb, srx->skb_offset, len, srx-
> >mpa_crc);
> }
>
> #define siw_dbg(ibdev, fmt, ...)
> \
> ibdev_dbg(ibdev, "%s: " fmt, __func__, ##__VA_ARGS__)
>
> --
> 2.49.0
>

Thanks Eric!
Works fine. Correct checksum tested against siw and cxgb4 peers.

Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>