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[net80211] First part of A-MSDU offload handling - don't bump A-MPDU reordering seqno

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When doing A-MSDU offload handling the driver is required to mark
A-MSDUs from the same MPDU with the same sequence number.
It then tags them as AMSDU (if it's a decap'ed A-MSDU) and AMSDU_MORE
(saying there's more AMSDUs decapped in the same MSDU.)
This allows encryption and sequence number offload to work right.

In the A-MSDU path the sequence number check looks at the A-MSDU flags
in the frame to see whether it's part of the same seqno and will pass them
(ie, not increment rx_seq until the last A-MSDU is seen from the driver,
or a new seqno shows up.0

However, I did this work in the A-MSDU path but not the A-MSDU in A-MPDU path.
For the non A-MDSU offload case the A-MPDU receive reordering will do its
thing and then pass up the MPDU up for decap - which then will see it's
an A-MSDU and decap each sub-frame.  But this isn't done for offloaded
A-MSDU frames.

This requires two parts:

* Don't bump the RX sequence number, same as above; and
* If frames go into the reordering buffer, they need to be added into the slot
  as a set of frames rather than a single frame, so once a new seqno shows up
  this slot can be marked as "full" and we can move on.

This patch does the first.  The latter requires that I find and commit
work to change rxa_m from an mbuf to an mbufq and the nhandle A-MSDU
there.  But, the first is enough to allow the normal case (ie, no or not
a lot of A-MPDU RX reordering) to work.

This allows the athp driver (QCA9880) throughput to go from VERY low
(like 5mbit TCP, 1/3-1/4 expected UDP throughput) to ~ 250mbit TCP
and > 300mbit UDP on a VHT/40 channel.  TCP sucks because, well, it
shows up as MASSIVE packet loss when all but one frame in a decap'ed
A-MSDU stream is dropped. Le whoops.

Now, where'd I put that laptop with the patch for rxa_m mbufq that
I wrote like in 2017...

Tested:

* AR9380, STA/AP mode (a big no-op, no A-MSDU hardware decap);
* if_run (RT3593), STA DWDS mode (A-MPDU / A-MSDU receive, but again
  no A-MSDU hardware decap);
* QCA9880, STA/AP mode (which is doing hardware A-MPDU/A-MSDU decap,
  but no A-MPDU reordering in the firmware.)
This commit is contained in:
Adrian Chadd 2020-06-12 04:19:03 +00:00
parent 2a73c8f5e1
commit a67acf111f
1 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
sys/net80211/ieee80211_ht.c
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@ -875,6 +875,7 @@ ieee80211_ampdu_reorder(struct ieee80211_node *ni, struct mbuf *m,
ieee80211_seq rxseq;
uint8_t tid;
int off;
int amsdu_more = ieee80211_check_rxseq_amsdu_more(rxs);
KASSERT((m->m_flags & (M_AMPDU | M_AMPDU_MPDU)) == M_AMPDU,
("!a-mpdu or already re-ordered, flags 0x%x", m->m_flags));
@ -949,10 +950,11 @@ again:
return CONSUMED;
} else {
/*
* In order; advance window and notify
* In order; advance window if needed and notify
* caller to dispatch directly.
*/
rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
if (amsdu_more)
rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
return PROCESS;
}
}
@ -996,7 +998,8 @@ again:
rap->rxa_qframes;
ampdu_rx_flush(ni, rap);
}
rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
if (amsdu_more)
rap->rxa_start = IEEE80211_SEQ_INC(rxseq);
return PROCESS;
}
} else {