Date: Tue, 21 Apr 2020 13:30:18 -0400 From: Mark Johnston <markj@freebsd.org> To: Eric Joyner <erj@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: Issue with epoch_drain_callbacks and unloading iavf(4) [using iflib] Message-ID: <20200421173018.GD86922@raichu> In-Reply-To: <CA%2Bb0zg9bi8Mc0ewnTqadjapHb5V-Mvc1y4c0AgZi08Q_Xy2dcg@mail.gmail.com> References: <CAKdFRZgm43LmjJ9dYDBGM8EV0ePRMLPr4YW_tPELANXQGpqpCA@mail.gmail.com> <CA%2Bb0zg_k=8nMhapa=T=yTcSJcUrrnG=AfQB%2Be0gPcCrgkbWtCQ@mail.gmail.com> <20200331192024.GE97238@raichu> <CA%2Bb0zg9z7srroWLtV_poedghXjCr0GvHv95cu4JzFrRdZoaeWw@mail.gmail.com> <20200406212903.GA55712@raichu> <CA%2Bb0zg-JM1rjO_OPh16sgM3Hm2hbzePNaW5bcxiL9aOpJ_vsOA@mail.gmail.com> <20200407232347.GA5605@raichu> <CA%2Bb0zg9DZys8v--Rwtg1qBkz8XbByehq6vr-xmLtjenNGgRKiQ@mail.gmail.com> <CA%2Bb0zg-swzucfwLZ4kmBKeE-g44L0EqRnft4wR8-_BataDgR%2Bg@mail.gmail.com> <CA%2Bb0zg9bi8Mc0ewnTqadjapHb5V-Mvc1y4c0AgZi08Q_Xy2dcg@mail.gmail.com>
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On Mon, Apr 20, 2020 at 04:39:07PM -0700, Eric Joyner wrote:
> On Thu, Apr 9, 2020 at 2:29 PM Eric Joyner <erj@freebsd.org> wrote:
>
> > On Thu, Apr 9, 2020 at 2:02 PM Eric Joyner <erj@freebsd.org> wrote:
> >
> >> On Tue, Apr 7, 2020 at 4:24 PM Mark Johnston <markj@freebsd.org> wrote:
> >>
> >>> I spent some time looking at the core. It looks like we have yet
> >>> another problem: the gtaskqueue code won't exit the net epoch if it is
> >>> constantly running a net task. Could you please retry with the patches
> >>> from before, and this one included?
> >>>
> >>> diff --git a/sys/kern/subr_gtaskqueue.c b/sys/kern/subr_gtaskqueue.c
> >>> index f52f32204644..2b1386a612ee 100644
> >>> --- a/sys/kern/subr_gtaskqueue.c
> >>> +++ b/sys/kern/subr_gtaskqueue.c
> >>> @@ -345,7 +345,7 @@ gtaskqueue_run_locked(struct gtaskqueue *queue)
> >>> struct epoch_tracker et;
> >>> struct gtaskqueue_busy tb;
> >>> struct gtask *gtask;
> >>> - bool in_net_epoch;
> >>> + bool in net_epoch;
> >>>
> >>> KASSERT(queue != NULL, ("tq is NULL"));
> >>> TQ_ASSERT_LOCKED(queue);
> >>> @@ -361,20 +361,19 @@ gtaskqueue_run_locked(struct gtaskqueue *queue)
> >>> TQ_UNLOCK(queue);
> >>>
> >>> KASSERT(gtask->ta_func != NULL, ("task->ta_func is
> >>> NULL"));
> >>> - if (!in_net_epoch && TASK_IS_NET(gtask)) {
> >>> - in_net_epoch = true;
> >>> + if (TASK_IS_NET(gtask)) {
> >>> NET_EPOCH_ENTER(et);
> >>> - } else if (in_net_epoch && !TASK_IS_NET(gtask)) {
> >>> + in_net_epoch = true;
> >>> + }
> >>> + gtask->ta_func(gtask->ta_context);
> >>> + if (in_net_epoch) {
> >>> NET_EPOCH_EXIT(et);
> >>> in_net_epoch = false;
> >>> }
> >>> - gtask->ta_func(gtask->ta_context);
> >>>
> >>> TQ_LOCK(queue);
> >>> wakeup(gtask);
> >>> }
> >>> - if (in_net_epoch)
> >>> - NET_EPOCH_EXIT(et);
> >>> LIST_REMOVE(&tb, tb_link);
> >>> }
> >>>
> >>> _______________________________________________
> >>> freebsd-net@freebsd.org mailing list
> >>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
> >>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
> >>>
> >>
> >> Yeah, I'll give it a spin and try to get back to you before the end of
> >> the week.
> >>
> >> - Eric
> >>
> >
> > I was able to try it out just now, and it looks this (and all of the other
> > patches) finally causes the problem to not appear! I can unload the driver
> > while iavf1 is receiving heavy traffic!
> >
> > - Eric
> >
>
> Hi Mark,
>
> Are you planning to commit these patches to HEAD? I see the reviews for
> D24214 and D24215 are still up, and I don't know if you created a review
> for the patch you put in this email chain.
Hi Eric,
Yes, I'm working on getting those patches reviewed and committed. The
patch above was just to verify a theory, we still need a proper
solution.
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