Drain grouptaskqueue of the gtask before detaching it.
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Authored by shurd on Oct 23 2018, 8:04 PM.

Details

Reviewers

erj
jeffrey.e.pieper_intel.com
krzysztof.galazka_intel.com

Group Reviewers

Intel Networking

Commits

rS340202: MFC r339861:
rS339861: Drain grouptaskqueue of the gtask before detaching it.

Summary

taskqgroup_detach() would remove the task even if it was
running or enqueued, which could lead to panics (see D17404). With
this change, taskqgroup_detach() drains the task and sets a new flag
which prevents the task from being scheduled again.

I've added grouptask_block() and grouptask_unblock() to allow control
over the flag from other locations as well.

Test Plan

Test with e1000 devices, and have Intel test with the initial
panicing testcase

Diff Detail

Repository

rS FreeBSD src repository - subversion

Lint

Lint Passed

Unit

No Test Coverage

Build Status

Buildable 20402
Build 19842: arc lint + arc unit

Event Timeline

shurd created this revision.Oct 23 2018, 8:04 PM

Herald added a subscriber: imp. · View Herald TranscriptOct 23 2018, 8:04 PM

Harbormaster completed remote builds in B20372: Diff 49528.Oct 23 2018, 8:04 PM

I tested this, as my laptop had panicked after updating from r339583 to r339639. I first updated sources to r339681, then applied the patch (via 'svn patch'); did the normal update, rebooted, and the em0 NIC worked just fine -- certainly no panic.

For reference:
FreeBSD 13.0-CURRENT #148 r339681M/339681: Wed Oct 24 05:48:37 PDT 2018 root@localhost:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY amd64 1300000

@shurd Thanks! That makes more sense than my version. I can't reproduce the ixl panic on my machine but Iets wait for an official verification by Jeff's team.

@dhw Thank you for testing the patch!

Add gtaskqueue_drain_locked() to hold common code for gtaskqueue_drain()
and grouptask_block().

Harbormaster completed remote builds in B20401: Diff 49570.Oct 24 2018, 5:18 PM

Add missing semi-colon.

Harbormaster completed remote builds in B20402: Diff 49571.Oct 24 2018, 5:30 PM

Given the changes, this morning, I:

Reverted the previous changes to sys/kern/subr_gtaskqueue.c and sys/sys/gtaskqueue.h
Updated sources from r339681to r339706
Applied the new diff (again, via 'svn patch')
Performed a normal source-based update

No panics or other issues; em0 NIC works.

We cannot reproduce the panic that was resolved with https://reviews.freebsd.org/D17404, so it looks okay to me.

This revision is now accepted and ready to land.Oct 26 2018, 12:49 PM

Closed by commit rS339861: Drain grouptaskqueue of the gtask before detaching it. (authored by shurd). · Explain WhyOct 29 2018, 2:36 PM

This revision was automatically updated to reflect the committed changes.