Re: [dpdk-dev] [PATCH v8 1/2] librte_net: add crc compute APIs

[Olivier Matz <olivier.matz@6wind.com>]

Hi Jasvinder,

On Thu, 30 Mar 2017 11:31:54 +0000, "Ananyev, Konstantin" <konstantin.ananyev@intel.com> wrote:
> Hi Jasvinder,
> 
> > diff --git a/lib/librte_net/rte_net_crc.h b/lib/librte_net/rte_net_crc.h
> > new file mode 100644
> > index 0000000..dd6c110
> > --- /dev/null
> > +++ b/lib/librte_net/rte_net_crc.h
> > @@ -0,0 +1,104 @@
> > +/*-
> > + *   BSD LICENSE
> > + *
> > + *   Copyright(c) 2017 Intel Corporation.
> > + *   All rights reserved.
> > + *
> > + *   Redistribution and use in source and binary forms, with or without
> > + *   modification, are permitted provided that the following conditions
> > + *   are met:
> > + *
> > + *     * Redistributions of source code must retain the above copyright
> > + *       notice, this list of conditions and the following disclaimer.
> > + *     * Redistributions in binary form must reproduce the above copyright
> > + *       notice, this list of conditions and the following disclaimer in
> > + *       the documentation and/or other materials provided with the
> > + *       distribution.
> > + *     * Neither the name of Intel Corporation nor the names of its
> > + *       contributors may be used to endorse or promote products derived
> > + *       from this software without specific prior written permission.
> > + *
> > + *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> > + *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> > + *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> > + *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> > + *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> > + *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> > + *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> > + *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> > + *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> > + *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> > + *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> > + */
> > +
> > +#ifndef _RTE_NET_CRC_H_
> > +#define _RTE_NET_CRC_H_
> > +
> > +#ifdef __cplusplus
> > +extern "C" {
> > +#endif
> > +
> > +#include <stdint.h>
> > +
> > +#include <rte_mbuf.h>  
> 
> As a nit: you probably don't need that include.
> Konstantin
> 
> > +
> > +/** CRC polynomials */
> > +#define CRC32_ETH_POLYNOMIAL 0x04c11db7UL
> > +#define CRC16_CCITT_POLYNOMIAL 0x1021U
> > +
> > +#define CRC_LUT_SIZE 256
> > +
> > +/** CRC types */
> > +enum rte_net_crc_type {
> > +	RTE_NET_CRC16_CCITT = 0,
> > +	RTE_NET_CRC32_ETH,
> > +	RTE_NET_CRC_REQS
> > +};
> > +
> > +/** CRC compute algorithm */
> > +enum rte_net_crc_alg {
> > +	RTE_NET_CRC_SCALAR = 0,
> > +	RTE_NET_CRC_SSE42,
> > +};
> > +
> > +/**
> > + * This API set the CRC computation algorithm (i.e. scalar version,
> > + * x86 64-bit sse4.2 intrinsic version, etc.) and internal data
> > + * structure.
> > + *
> > + * @param alg
> > + *   This parameter is used to select the CRC implementation version.
> > + *   - RTE_NET_CRC_SCALAR
> > + *   - RTE_NET_CRC_SSE42 (Use 64-bit SSE4.2 intrinsic)
> > + */
> > +void
> > +rte_net_crc_set_alg(enum rte_net_crc_alg alg);
> > +
> > +/**
> > + * CRC compute API
> > + *
> > + * @param data
> > + *   Pointer to the packet data for CRC computation
> > + * @param data_len
> > + *   Data length for CRC computation
> > + * @param type
> > + *   CRC type (enum rte_net_crc_type)
> > + *
> > + * @return
> > + *   CRC value
> > + */
> > +uint32_t
> > +rte_net_crc_calc(const void *data,
> > +	uint32_t data_len,
> > +	enum rte_net_crc_type type);
> > +
> > +#if defined(RTE_ARCH_X86_64) && defined(RTE_MACHINE_CPUFLAG_SSE4_2)
> > +#include <rte_net_crc_sse.h>
> > +#endif

I think this include should not be included from rte_net_crc.h.

From what I see, the API is the same for sse and non-sse, so this include
could be private, included only from the .c file. If you also remove
the include to rte_mbuf.h as suggested by Konstantin, it will require the
following includes in rte_net_crc.c:

 #include <stddef.h>
 #include <string.h>
 
 #include <rte_common.h>
 #include <rte_cpuflags.h>
 #include <rte_branch_prediction.h>
 #include <rte_vect.h>
 #include <rte_net_crc.h>
 #if defined(RTE_ARCH_X86_64) && defined(RTE_MACHINE_CPUFLAG_SSE4_2)
 #include <rte_net_crc_sse.h>
 #endif

If the sse file is only used in the .c, this line could also be
removed in the Makefile:

SYMLINK-$(CONFIG_RTE_LIBRTE_NET)-include += rte_net_crc_sse.h


I'm not very familiar with crc and sse code. Could you add yourself
as maintainer for these files in MAINTAINERS?


Thanks
Olivier