Re: [dpdk-dev] [RFC PATCH] mbuf: move headers not fragmented check to checksum

["Wiles, Keith" <keith.wiles@intel.com>]

> On Feb 13, 2019, at 3:50 AM, Andrew Rybchenko <arybchenko@solarflare.com> wrote:
> 
> Ping.
> 
> Do 2 weeks without reply mean that it looks good and I should send non-RCF version?

Just send the non-RFC patch as it seems most do not even look at the RFC’s anyway.
> 
> Andrew.
> 
> On 1/29/19 11:49 AM, Andrew Rybchenko wrote:
>> rte_validate_tx_offload() is used in Tx prepare callbacks
>> (RTE_LIBRTE_ETHDEV_DEBUG only) to check Tx offloads consistency.
>> Requirement that packet headers should not be fragmented is not
>> documented and unclear where it comes from except
>> rte_net_intel_cksum_prepare() functions which relies on it.
>> 
>> It could be NIC vendor specific driver or hardware limitation, but,
>> if so, it should be documented and checked in corresponding Tx
>> prepare callbacks.
>> 
>> Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
>> ---
>> May be the check should be done in rte_net_intel_cksum_prepare()
>> under RTE_LIBRTE_ETHDEV_DEBUG only. Mainly I'd like to get feedback
>> on where the limitation comes from and idea to remove it from
>> rte_validate_tx_offload().
>> 
>>  lib/librte_mbuf/rte_mbuf.h | 12 ------------
>>  lib/librte_net/rte_net.h   | 17 +++++++++++++++++
>>  2 files changed, 17 insertions(+), 12 deletions(-)
>> 
>> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
>> index a7f67023a..14a3b472b 100644
>> --- a/lib/librte_mbuf/rte_mbuf.h
>> +++ b/lib/librte_mbuf/rte_mbuf.h
>> @@ -2257,23 +2257,11 @@ static inline int
>>  rte_validate_tx_offload(const struct rte_mbuf *m)
>>  {
>>  	uint64_t ol_flags = m->ol_flags;
>> -	uint64_t inner_l3_offset = m->l2_len;
>>    	/* Does packet set any of available offloads? */
>>  	if (!(ol_flags & PKT_TX_OFFLOAD_MASK))
>>  		return 0;
>>  -	if (ol_flags & PKT_TX_OUTER_IP_CKSUM)
>> -		/* NB: elaborating the addition like this instead of using
>> -		 *     += gives the result uint64_t type instead of int,
>> -		 *     avoiding compiler warnings on gcc 8.1 at least */
>> -		inner_l3_offset = inner_l3_offset + m->outer_l2_len +
>> -				  m->outer_l3_len;
>> -
>> -	/* Headers are fragmented */
>> -	if (rte_pktmbuf_data_len(m) < inner_l3_offset + m->l3_len + m->l4_len)
>> -		return -ENOTSUP;
>> -
>>  	/* IP checksum can be counted only for IPv4 packet */
>>  	if ((ol_flags & PKT_TX_IP_CKSUM) && (ol_flags & PKT_TX_IPV6))
>>  		return -EINVAL;
>> diff --git a/lib/librte_net/rte_net.h b/lib/librte_net/rte_net.h
>> index e59760a0a..bd75aea8e 100644
>> --- a/lib/librte_net/rte_net.h
>> +++ b/lib/librte_net/rte_net.h
>> @@ -118,10 +118,27 @@ rte_net_intel_cksum_flags_prepare(struct rte_mbuf *m, uint64_t ol_flags)
>>  	struct udp_hdr *udp_hdr;
>>  	uint64_t inner_l3_offset = m->l2_len;
>>  +	/*
>> +	 * Does packet set any of available offloads?
>> +	 * Mainly it is required to avoid fragmented headers check if
>> +	 * no offloads are requested.
>> +	 */
>> +	if (!(ol_flags & PKT_TX_OFFLOAD_MASK))
>> +		return 0;
>> +
>>  	if ((ol_flags & PKT_TX_OUTER_IP_CKSUM) ||
>>  		(ol_flags & PKT_TX_OUTER_IPV6))
>>  		inner_l3_offset += m->outer_l2_len + m->outer_l3_len;
>>  +	/*
>> +	 * Check if headers are fragmented.
>> +	 * The check could be less strict depending on which offloads are
>> +	 * requested and headers to be used, but let's keep it simple.
>> +	 */
>> +	if (unlikely(rte_pktmbuf_data_len(m) <
>> +		     inner_l3_offset + m->l3_len + m->l4_len))
>> +		return -ENOTSUP;
>> +
>>  	if (ol_flags & PKT_TX_IPV4) {
>>  		ipv4_hdr = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *,
>>  				inner_l3_offset);
> 

Regards,
Keith