On Thu, 19 Apr 2018 16:14:25 +0200 Pierre Morel <[email protected]> wrote:
> On 13/04/2018 16:05, Cornelia Huck wrote: > > When we call ssch, an interrupt might already be pending once we > > return from the START SUBCHANNEL instruction. Therefore we need to > > make sure interrupts are disabled until after we're done with our > > processing. > > > > Note that the subchannel lock is the same as the ccwdevice lock that > > is mentioned in the documentation for ccw_device_start() and friends. > > > > Signed-off-by: Cornelia Huck <[email protected]> > > --- > > drivers/s390/cio/vfio_ccw_fsm.c | 19 ++++++++++++------- > > 1 file changed, 12 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/s390/cio/vfio_ccw_fsm.c > > b/drivers/s390/cio/vfio_ccw_fsm.c > > index ff6963ad6e39..3c800642134e 100644 > > --- a/drivers/s390/cio/vfio_ccw_fsm.c > > +++ b/drivers/s390/cio/vfio_ccw_fsm.c > > @@ -20,12 +20,12 @@ static int fsm_io_helper(struct vfio_ccw_private > > *private) > > int ccode; > > __u8 lpm; > > unsigned long flags; > > + int ret; > > > > sch = private->sch; > > > > spin_lock_irqsave(sch->lock, flags); > > private->state = VFIO_CCW_STATE_BUSY; > > - spin_unlock_irqrestore(sch->lock, flags); > > > > orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm); > > > > @@ -38,10 +38,12 @@ static int fsm_io_helper(struct vfio_ccw_private > > *private) > > * Initialize device status information > > */ > > sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND; > > - return 0; > > + ret = 0; > > + break; > > case 1: /* Status pending */ > > case 2: /* Busy */ > > - return -EBUSY; > > + ret = -EBUSY; > > + break; > > case 3: /* Device/path not operational */ > > { > > lpm = orb->cmd.lpm; > > @@ -51,13 +53,16 @@ static int fsm_io_helper(struct vfio_ccw_private > > *private) > > sch->lpm = 0; > > > > if (cio_update_schib(sch)) > > - return -ENODEV; > > - > > - return sch->lpm ? -EACCES : -ENODEV; > > + ret = -ENODEV; > > + else > > + ret = sch->lpm ? -EACCES : -ENODEV; > > + break; > > } > > default: > > - return ccode; > > + ret = ccode; > > } > > + spin_unlock_irqrestore(sch->lock, flags); > > + return ret; > > } > > > > static void fsm_notoper(struct vfio_ccw_private *private, > > > I have been working on a patch to solve this problem between others, I > provide it soon. > It is much more intrusive, reworking interrupts and state machine. > So may be you do not like it. I'll take a look at your state machine series later, but it is certainly material for the next release. [I also have my halt/clear implementation which I wanted to send this week, but other things have been eating up my bandwidth. Well, the week is not over yet...] > If we stay on this patch, even this is quite a long spinlock around ssch > and stsch, > and we need it in the current implementation. I'd like to queue a small patch like this for the current release which is also suitable for stable. We can still rework things on top. > Acked-by: Pierre Morel<[email protected]> Thanks!
