Re: [dpdk-stable] [PATCH] net/enic: fix TSO for packets greater than 9208 bytes

["John Daley (johndale)" <johndale@cisco.com>]

> -----Original Message-----
> From: Luca Boccassi [mailto:bluca@debian.org]
> Sent: Friday, November 03, 2017 3:00 AM
> To: John Daley (johndale) <johndale@cisco.com>; johnda888@gmail.com
> Cc: stable@dpdk.org
> Subject: Re: [dpdk-stable] [PATCH] net/enic: fix TSO for packets greater than
> 9208 bytes
> 
> On Wed, 2017-11-01 at 18:56 -0700, John Daley wrote:
> > A check was previously added to drop Tx packets greater than what the
> > Nic is capable of sending since such packets can freeze the send
> > queue.
> > The
> > check did not account for TSO packets however, so TSO was limited to
> > 9208
> > bytes.
> >
> > Check packet length only for non-TSO packets. Also insure that TSO
> > packet segment size plus the headers do not exceed what the Nic is
> > capable of since this also can freeze the send queue.
> >
> > Use the PKT_TX_TCP_SEG ol_flag instead of m->tso_segsz which is the
> > preferred way to check for TSO.
> >
> > Fixes: ed6e564c214e ("net/enic: fix memory leak with oversized Tx
> > packets")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: John Daley <johndale@cisco.com>
> > ---
> >
> > Note that there is some more work to do on enic TSO- the header length
> > is calculated by looking at the packet instead of just trusting mbuf
> > tso offload header lengths. The 'tx_oversized' stat is used for more
> > than just oversized packets- it gets rolled into 'oerrors' so doesn't
> > matter but the name should be changed. Some TSO tunneling support can
> > be added for newer hardware. These changes will come in the next
> > relase, but hope that this patch can be accepted in 17.11 because it
> > solves existing customer problem.
> >
> >  drivers/net/enic/enic_rxtx.c | 25 +++++++++++++++++++------
> >  1 file changed, 19 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/net/enic/enic_rxtx.c
> > b/drivers/net/enic/enic_rxtx.c index a39172f14..e938193b5 100644
> > --- a/drivers/net/enic/enic_rxtx.c
> > +++ b/drivers/net/enic/enic_rxtx.c
> > @@ -546,12 +546,15 @@ uint16_t enic_xmit_pkts(void *tx_queue, struct
> > rte_mbuf **tx_pkts,
> >  	uint64_t bus_addr;
> >  	uint8_t offload_mode;
> >  	uint16_t header_len;
> > +	uint64_t tso;
> > +	rte_atomic64_t *tx_oversized;
> >
> >  	enic_cleanup_wq(enic, wq);
> >  	wq_desc_avail = vnic_wq_desc_avail(wq);
> >  	head_idx = wq->head_idx;
> >  	desc_count = wq->ring.desc_count;
> >  	ol_flags_mask = PKT_TX_VLAN_PKT | PKT_TX_IP_CKSUM |
> PKT_TX_L4_MASK;
> > +	tx_oversized = &enic->soft_stats.tx_oversized;
> >
> >  	nb_pkts = RTE_MIN(nb_pkts, ENIC_TX_XMIT_MAX);
> >
> > @@ -561,10 +564,12 @@ uint16_t enic_xmit_pkts(void *tx_queue, struct
> > rte_mbuf **tx_pkts,
> >  		data_len = tx_pkt->data_len;
> >  		ol_flags = tx_pkt->ol_flags;
> >  		nb_segs = tx_pkt->nb_segs;
> > +		tso = ol_flags & PKT_TX_TCP_SEG;
> >
> > -		if (pkt_len > ENIC_TX_MAX_PKT_SIZE) {
> > +		/* drop packet if it's too big to send */
> > +		if (unlikely(!tso && (pkt_len >
> > ENIC_TX_MAX_PKT_SIZE))) {
> >  			rte_pktmbuf_free(tx_pkt);
> > -			rte_atomic64_inc(&enic-
> > >soft_stats.tx_oversized);
> > +			rte_atomic64_inc(tx_oversized);
> >  			continue;
> >  		}
> >
> > @@ -587,13 +592,21 @@ uint16_t enic_xmit_pkts(void *tx_queue, struct
> > rte_mbuf **tx_pkts,
> >  		offload_mode = WQ_ENET_OFFLOAD_MODE_CSUM;
> >  		header_len = 0;
> >
> > -		if (tx_pkt->tso_segsz) {
> > +		if (tso) {
> >  			header_len = tso_header_len(tx_pkt);
> > -			if (header_len) {
> > -				offload_mode =
> > WQ_ENET_OFFLOAD_MODE_TSO;
> > -				mss = tx_pkt->tso_segsz;
> > +
> > +			/* Drop if non-TCP packet or TSO seg size is
> > too big */
> > +			if (unlikely((header_len == 0) || ((tx_pkt-
> > >tso_segsz +
> > +			    header_len) > ENIC_TX_MAX_PKT_SIZE))) {
> > +				rte_pktmbuf_free(tx_pkt);
> > +				rte_atomic64_inc(tx_oversized);
> > +				continue;
> >  			}
> > +
> > +			offload_mode = WQ_ENET_OFFLOAD_MODE_TSO;
> > +			mss = tx_pkt->tso_segsz;
> >  		}
> > +
> >  		if ((ol_flags & ol_flags_mask) && (header_len == 0)) {
> >  			if (ol_flags & PKT_TX_IP_CKSUM)
> >  				mss |= ENIC_CALC_IP_CKSUM;
> 
> Hi,
> 
> Has this, or a version of this, been accepted into dpdk/master? I did a quick
> search but couldn't find it.

My apologies, this version of the fix was not supposed to get out into the wild.
The patch I submitted that was accepted into dpdk-next-net is f12766f72.

> 
> I tried to apply it to dpdk-stable/16.11 but the context is quite different so it
> doesn't apply. If you would like it for 16.11.4, after it's accepted in
> dpdk/master, please send a reworked version that can be applied to dpdk-
> stable/16.11.

You are correct, the feature being patched (TSO) did not exist in 16.11 so the patch doesn't apply. It does apply to the 17.05 stable branch. Please apply it there if a 17.05.3 is going to be created. Sorry again for the confusion.
> 
> Thanks!
> 
> --
> Kind regards,
> Luca Boccassi