Re: [dpdk-dev] [PATCH] i40e: Use one bit flag for all hardware detected RX packet errors

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Helin,

> -----Original Message-----
> From: Zhang, Helin
> Sent: Wednesday, November 26, 2014 6:07 AM
> To: dev@dpdk.org
> Cc: Cao, Waterman; Cao, Min; Ananyev, Konstantin; olivier.matz@6wind.com; Zhang, Helin
> Subject: [PATCH] i40e: Use one bit flag for all hardware detected RX packet errors
> 
> There were some bit flags of 0 for RX packet errors detected by hardware.
> Actually only one bit of error flag is enough for all hardware detected
> RX packet errors.
> 
> Signed-off-by: Helin Zhang <helin.zhang@intel.com>
> ---
>  lib/librte_mbuf/rte_mbuf.h      |  6 +-----
>  lib/librte_pmd_i40e/i40e_rxtx.c | 31 +++----------------------------
>  2 files changed, 4 insertions(+), 33 deletions(-)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 5899e5c..897fd26 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -80,11 +80,6 @@ extern "C" {
>  #define PKT_RX_FDIR          (1ULL << 2)  /**< RX packet with FDIR match indicate. */
>  #define PKT_RX_L4_CKSUM_BAD  (1ULL << 3)  /**< L4 cksum of RX pkt. is not OK. */
>  #define PKT_RX_IP_CKSUM_BAD  (1ULL << 4)  /**< IP cksum of RX pkt. is not OK. */
> -#define PKT_RX_EIP_CKSUM_BAD (0ULL << 0)  /**< External IP header checksum error. */
> -#define PKT_RX_OVERSIZE      (0ULL << 0)  /**< Num of desc of an RX pkt oversize. */
> -#define PKT_RX_HBUF_OVERFLOW (0ULL << 0)  /**< Header buffer overflow. */
> -#define PKT_RX_RECIP_ERR     (0ULL << 0)  /**< Hardware processing error. */
> -#define PKT_RX_MAC_ERR       (0ULL << 0)  /**< MAC error. */
>  #define PKT_RX_IPV4_HDR      (1ULL << 5)  /**< RX packet with IPv4 header. */
>  #define PKT_RX_IPV4_HDR_EXT  (1ULL << 6)  /**< RX packet with extended IPv4 header. */
>  #define PKT_RX_IPV6_HDR      (1ULL << 7)  /**< RX packet with IPv6 header. */
> @@ -95,6 +90,7 @@ extern "C" {
>  #define PKT_RX_TUNNEL_IPV6_HDR (1ULL << 12) /**< RX tunnel packet with IPv6 header. */
>  #define PKT_RX_FDIR_ID       (1ULL << 13) /**< FD id reported if FDIR match. */
>  #define PKT_RX_FDIR_FLX      (1ULL << 14) /**< Flexible bytes reported if FDIR match. */
> +#define PKT_RX_ERR_HW        (1ULL << 15) /**< RX packet error detected by hardware. */
> 
>  #define PKT_TX_VLAN_PKT      (1ULL << 55) /**< TX packet is a 802.1q VLAN packet. */
>  #define PKT_TX_IP_CKSUM      (1ULL << 54) /**< IP cksum of TX pkt. computed by NIC. */
> diff --git a/lib/librte_pmd_i40e/i40e_rxtx.c b/lib/librte_pmd_i40e/i40e_rxtx.c
> index cce6911..3b2195d 100644
> --- a/lib/librte_pmd_i40e/i40e_rxtx.c
> +++ b/lib/librte_pmd_i40e/i40e_rxtx.c
> @@ -115,35 +115,10 @@ i40e_rxd_status_to_pkt_flags(uint64_t qword)
>  static inline uint64_t
>  i40e_rxd_error_to_pkt_flags(uint64_t qword)
>  {
> -	uint64_t flags = 0;
> -	uint64_t error_bits = (qword >> I40E_RXD_QW1_ERROR_SHIFT);
> -
> -#define I40E_RX_ERR_BITS 0x3f
> -	if (likely((error_bits & I40E_RX_ERR_BITS) == 0))
> -		return flags;
> -	/* If RXE bit set, all other status bits are meaningless */
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_RXE_SHIFT))) {
> -		flags |= PKT_RX_MAC_ERR;
> -		return flags;
> -	}
> -
> -	/* If RECIPE bit set, all other status indications should be ignored */
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_RECIPE_SHIFT))) {
> -		flags |= PKT_RX_RECIP_ERR;
> -		return flags;
> -	}
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_HBO_SHIFT)))
> -		flags |= PKT_RX_HBUF_OVERFLOW;
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_IPE_SHIFT)))
> -		flags |= PKT_RX_IP_CKSUM_BAD;
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_L4E_SHIFT)))
> -		flags |= PKT_RX_L4_CKSUM_BAD;
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_EIPE_SHIFT)))
> -		flags |= PKT_RX_EIP_CKSUM_BAD;
> -	if (unlikely(error_bits & (1 << I40E_RX_DESC_ERROR_OVERSIZE_SHIFT)))
> -		flags |= PKT_RX_OVERSIZE;
> +	if (unlikely(qword & I40E_RXD_QW1_ERROR_MASK))
> +		return PKT_RX_ERR_HW;

Probably I didn't explain myself clear enough, sorry.
I didn't suggest to get rid of setting bits that indicate L3/L4 checksum errors:
PKT_RX_IP_CKSUM_BAD, PKT_RX_L4_CKSUM_BAD, PKT_RX_EIP_CKSUM_BAD.
I think these flags should be set as before.

I was talking only about collapsing only these 4 RX error flags into one:

#define PKT_RX_OVERSIZE      (0ULL << 0)  /**< Num of desc of an RX pkt oversize. */
#define PKT_RX_HBUF_OVERFLOW (0ULL << 0)  /**< Header buffer overflow. */
#define PKT_RX_RECIP_ERR     (0ULL << 0)  /**< Hardware processing error. */
#define PKT_RX_MAC_ERR       (0ULL << 0)  /**< MAC error. */ 

>From my point of view the difference of these 2 groups are:
First - HW was able to receive whole packet without a problem, but L3/L4 checksum check failed.

Second - HW was not able to receive whole packet properly by whatever reason. 
>From upper layer SW perspective - there it probably makes little difference, what caused it,
as most likely SW has to throw away erroneous packet. 
And for debugging purposes, we can add PMD_LOG(DEBUG, ...) that would print what exactly HW error happened.

Thanks
Konstantin

> 
> -	return flags;
> +	return 0;
>  }
> 
>  /* Translate pkt types to pkt flags */
> --
> 1.8.1.4