On Mon, 15 Apr 2019 09:38:37 -0400 Farhan Ali <alifm@xxxxxxxxxxxxx> wrote: > On 04/15/2019 04:13 AM, Cornelia Huck wrote: > > On Fri, 12 Apr 2019 10:38:50 -0400 > > Farhan Ali <alifm@xxxxxxxxxxxxx> wrote: > > > >> On 04/12/2019 04:10 AM, Cornelia Huck wrote: > >>> On Thu, 11 Apr 2019 16:30:44 -0400 > >>> Farhan Ali <alifm@xxxxxxxxxxxxx> wrote: > >>> > >>>> On 04/11/2019 12:24 PM, Cornelia Huck wrote: > >>>>> On Mon, 8 Apr 2019 17:05:32 -0400 > >>>>> Farhan Ali <alifm@xxxxxxxxxxxxx> wrote: > > > >>>>> Looking at the possible return codes: > >>>>> * -ENODEV -> device is not operational anyway, in theory you should even > >>>>> not need to bother with disabling the subchannel > >>>>> * -EIO -> we've run out of retries, and the subchannel still is not > >>>>> idle; I'm not sure if we could do anything here, as disable is > >>>>> unlikely to work, either > > > > (...) > > > >> Thinking a little bit more about EIO, if the return code is EIO then it > >> means we have exhausted all our options with cancel_halt_clear and the > >> subchannel/device is still status pending, right? > > > > Yes. > > > >> > >> I think we should still continue to try and disable the subchannel, > >> because if not then the subchannel/device could in some point of time > >> come back and bite us. So we really should protect the system from this > >> behavior. > > > > I think trying to disable the subchannel does not really hurt, but I > > fear it won't succeed in that case... > > > >> > >> I think for EIO we should log an error message, but still try to > >> continue with disabling the subchannel. What do you or others think? > > > > Logging an error may be useful (it's really fouled up at that time), but... > > > >> > >> > >> > >> > >>>> > >>>>>> + flush_workqueue(vfio_ccw_work_q); > >>>>>> + spin_lock_irq(sch->lock); > >>>>>> ret = cio_disable_subchannel(sch); > > > > ...there's a good chance that we'd get -EBUSY here, which would keep us > > in the loop. We probably need to break out after we got -EIO from > > cancel_halt_clear, regardless of which return code we get from the > > disable. > > Okay, for EIO we can log an error message and break out of the loop. > > I will send a v3. Are you going to queue patch 1 or patch 3 soon? If you > are then I will just send this patch separately. Yes, please do send it separately. I'm currently testing patch 1 and 3 on top of my patchset, will queue either with or without the halt/clear patches proper, depending on how soon I get acks/r-bs (hint, hint :) > > Thanks > Farhan > > > > > (It will be "interesting" to see what happens with such a stuck > > subchannel in the calling code; but I don't really see many options. > > Panic seems way too strong; maybe mark the subchannel as "broken; no > > idea how to fix"? But that would be a follow-on patch; I think if we > > avoid the endless loop here, this patch is a real improvement and > > should just go in.) > > > >>>>>> } while (ret == -EBUSY); > >>>>>> out_unlock: > >>>>> > >>>>> > >>>> > >>> > >>> > >> > > > > >
