iflib: update rs_pending based on descriptors consumed by isc_txd_encap
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Authored by gallatin on Wed, Sep 2, 1:01 PM.

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kbowling
netchild
shurd

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iflib

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rGa5bb0fde6722: iflib: update rs_pending based on descriptors consumed by isc_txd_encap

Summary

The new watchdog code is triggering spurious watchdog resets on my out-of-tree NICs using ktls.

The issue is that rs_pending is updated using the descriptors for the current packet, based on what bus_dma produced.
However, NICs which support ktls offload may do extra DMAs (and consume extra segs) to derive crypto state when re-transmitting
TLS segments. This is the reason for allowing drivers to control ift_pad. When this happens, rs_pending may
be undercounted. This was harmless before, but is causing spurious watchdog resets now.

Fix this by using the actual segments consumed by the NICs isc_txd_encap.

Note this removes this historical overcount by one.

This patch has been stable on my test hardware (in combination with https://reviews.freebsd.org/D59204)

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rG FreeBSD src repository

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gallatin created this revision.Wed, Sep 2, 1:01 PM

Herald added a reviewer: shurd. · View Herald TranscriptWed, Sep 2, 1:02 PM

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gallatin requested review of this revision.Wed, Sep 2, 1:02 PM

I think this is a strict accounting improvement. e1000 manufactures some descriptors in a couple situations to work around hw errata, although I'm not sure that direct RS wb would've faulted.

This revision is now accepted and ready to land.Wed, Sep 2, 4:38 PM

kgalazka added a subscriber: kgalazka.Wed, Sep 2, 7:49 PM

kgalazka added inline comments.

sys/net/iflib.c
2462	nit: extra dot
3771–3775	@kbowling Fixed honoring IPI_TX_INTR in IAVF and IXL, but ICE still ignores it. I'll take care of that. Do you think this can cause any issues until ICE is fixed?

kbowling added inline comments.Wed, Sep 2, 11:17 PM

sys/net/iflib.c
3771–3775	See D58910. Without D58910 ice does RS wb for every packet, and the watchdog is a little less sensitive, but no false watchdog risk and these can land in any order.