From: Cornelia Huck <firstname.lastname@example.org> To: Eric Farman <email@example.com> Cc: Halil Pasic <firstname.lastname@example.org>, Matthew Rosato <email@example.com>, Jared Rossi <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org Subject: Re: [RFC PATCH v4 2/4] vfio-ccw: Check workqueue before doing START Date: Fri, 16 Apr 2021 16:41:37 +0200 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On Thu, 15 Apr 2021 14:42:21 -0400 Eric Farman <email@example.com> wrote: > On Thu, 2021-04-15 at 18:19 +0200, Cornelia Huck wrote: > > On Thu, 15 Apr 2021 09:48:37 -0400 > > Eric Farman <firstname.lastname@example.org> wrote: > > > > > On Thu, 2021-04-15 at 12:51 +0200, Cornelia Huck wrote: > > > > I'm wondering what we should do for hsch. We probably want to > > > > return > > > > -EBUSY for a pending condition as well, if I read the PoP > > > > correctly... > > > > > > Ah, yes... I agree that to maintain parity with ssch and pops, the > > > same cc1/-EBUSY would be applicable here. Will make that change in > > > next > > > version. > > > > Yes, just to handle things in the same fashion consistently. > > > > > > the only problem is that QEMU seems to match everything to 0; but > > > > that > > > > is arguably not the kernel's problem. > > > > > > > > For clear, we obviously don't have busy conditions. Should we > > > > clean > > > > up > > > > any pending conditions? > > > > > > By doing anything other than issuing the csch to the subchannel? I > > > don't think so, that should be more than enough to get the css and > > > vfio-ccw in sync with each other. > > > > Hm, doesn't a successful csch clear any status pending? > > Yep. > > > That would mean > > that invoking our csch backend implies that we won't deliver the > > status > > pending that is already pending via the workqueue, which therefore > > needs to be flushed out in some way? > > Ah, so I misunderstood the direction you were going... I'm not aware of > a way to "purge" items from a workqueue, as the flush_workqueue() > routine is documented as picking them off and running them. > > Perhaps an atomic flag in (private? cp?) that causes > vfio_ccw_sch_io_todo() to just exit rather than doing all its stuff? Yes, maybe something like that. Maybe we should do that on top once we have a good idea, if the current series already fixes the problems that are actually happening now and then. > > > I remember we did some special > > csch handling, but I don't immediately see where; might have been > > only > > in QEMU. > > > > Maybe. I don't see anything jumping out at me though. :( I might have misremembered; it only really applies to passthrough, as emulated subchannels are handled synchronously anyway.
next prev parent reply other threads:[~2021-04-16 14:41 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-13 18:24 [RFC PATCH v4 0/4] vfio-ccw: Fix interrupt handling for HALT/CLEAR Eric Farman 2021-04-13 18:24 ` [RFC PATCH v4 1/4] vfio-ccw: Check initialized flag in cp_init() Eric Farman 2021-04-14 16:30 ` Cornelia Huck 2021-04-13 18:24 ` [RFC PATCH v4 2/4] vfio-ccw: Check workqueue before doing START Eric Farman 2021-04-15 10:51 ` Cornelia Huck 2021-04-15 13:48 ` Eric Farman 2021-04-15 16:19 ` Cornelia Huck 2021-04-15 18:42 ` Eric Farman 2021-04-16 14:41 ` Cornelia Huck [this message] 2021-04-13 18:24 ` [RFC PATCH v4 3/4] vfio-ccw: Reset FSM state to IDLE inside FSM Eric Farman 2021-04-15 10:54 ` Cornelia Huck 2021-04-13 18:24 ` [RFC PATCH v4 4/4] vfio-ccw: Reset FSM state to IDLE before io_mutex Eric Farman 2021-04-21 10:25 ` Cornelia Huck 2021-04-21 12:58 ` Eric Farman 2021-04-22 16:16 ` Eric Farman 2021-04-22 0:52 ` [RFC PATCH v4 0/4] vfio-ccw: Fix interrupt handling for HALT/CLEAR Halil Pasic 2021-04-22 20:49 ` Eric Farman 2021-04-23 11:06 ` Cornelia Huck 2021-04-23 13:23 ` Halil Pasic 2021-04-23 13:28 ` Niklas Schnelle 2021-04-23 15:53 ` Eric Farman 2021-04-23 11:50 ` Halil Pasic 2021-04-23 15:53 ` Eric Farman 2021-04-23 17:08 ` Halil Pasic 2021-04-23 19:07 ` Eric Farman 2021-04-24 0:18 ` Halil Pasic
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