From: Cornelia Huck <cohuck@redhat.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, Eric Farman <farman@linux.ibm.com>,
Pierre Morel <pmorel@linux.ibm.com>,
kvm@vger.kernel.org, qemu-s390x@nongnu.org,
Farhan Ali <alifm@linux.ibm.com>,
qemu-devel@nongnu.org,
Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [PATCH v2 2/5] vfio-ccw: concurrent I/O handling
Date: Tue, 22 Jan 2019 11:29:26 +0100 [thread overview]
Message-ID: <20190122112926.4ff54f9f.cohuck@redhat.com> (raw)
In-Reply-To: <20190121212018.4e377e59@oc2783563651>
On Mon, 21 Jan 2019 21:20:18 +0100
Halil Pasic <pasic@linux.ibm.com> wrote:
> On Mon, 21 Jan 2019 12:03:51 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
> > Rework handling of multiple I/O requests to return -EAGAIN if
> > we are already processing an I/O request. Introduce a mutex
> > to disallow concurrent writes to the I/O region.
> >
> > The expectation is that userspace simply retries the operation
> > if it gets -EAGAIN.
> >
> > We currently don't allow multiple ssch requests at the same
> > time, as we don't have support for keeping channel programs
> > around for more than one request.
> >
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
>
> [..]
>
> > static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
> > @@ -188,25 +192,30 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
> > {
> > struct vfio_ccw_private *private;
> > struct ccw_io_region *region;
> > + int ret;
> >
> > if (*ppos + count > sizeof(*region))
> > return -EINVAL;
> >
> > private = dev_get_drvdata(mdev_parent_dev(mdev));
> > - if (private->state != VFIO_CCW_STATE_IDLE)
> > + if (private->state == VFIO_CCW_STATE_NOT_OPER ||
> > + private->state == VFIO_CCW_STATE_STANDBY)
> > return -EACCES;
> > + if (!mutex_trylock(&private->io_mutex))
> > + return -EAGAIN;
> >
> > region = private->io_region;
> > - if (copy_from_user((void *)region + *ppos, buf, count))
> > - return -EFAULT;
> > + if (copy_from_user((void *)region + *ppos, buf, count)) {
>
> This might race with vfio_ccw_sch_io_todo() on
> private->io_region->irb_area, or?
Ah yes, this should also take the mutex (should work because we're on a
workqueue).
>
> > + ret = -EFAULT;
> > + goto out_unlock;
> > + }
> >
> > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
> > - if (region->ret_code != 0) {
> > - private->state = VFIO_CCW_STATE_IDLE;
> > - return region->ret_code;
> > - }
> > + ret = (region->ret_code != 0) ? region->ret_code : count;
> >
> > - return count;
> > +out_unlock:
> > + mutex_unlock(&private->io_mutex);
> > + return ret;
> > }
> >
> [..]
>
WARNING: multiple messages have this Message-ID (diff)
From: Cornelia Huck <cohuck@redhat.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: Eric Farman <farman@linux.ibm.com>,
Farhan Ali <alifm@linux.ibm.com>,
Pierre Morel <pmorel@linux.ibm.com>,
linux-s390@vger.kernel.org, kvm@vger.kernel.org,
Alex Williamson <alex.williamson@redhat.com>,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 2/5] vfio-ccw: concurrent I/O handling
Date: Tue, 22 Jan 2019 11:29:26 +0100 [thread overview]
Message-ID: <20190122112926.4ff54f9f.cohuck@redhat.com> (raw)
In-Reply-To: <20190121212018.4e377e59@oc2783563651>
On Mon, 21 Jan 2019 21:20:18 +0100
Halil Pasic <pasic@linux.ibm.com> wrote:
> On Mon, 21 Jan 2019 12:03:51 +0100
> Cornelia Huck <cohuck@redhat.com> wrote:
>
> > Rework handling of multiple I/O requests to return -EAGAIN if
> > we are already processing an I/O request. Introduce a mutex
> > to disallow concurrent writes to the I/O region.
> >
> > The expectation is that userspace simply retries the operation
> > if it gets -EAGAIN.
> >
> > We currently don't allow multiple ssch requests at the same
> > time, as we don't have support for keeping channel programs
> > around for more than one request.
> >
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
>
> [..]
>
> > static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
> > @@ -188,25 +192,30 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
> > {
> > struct vfio_ccw_private *private;
> > struct ccw_io_region *region;
> > + int ret;
> >
> > if (*ppos + count > sizeof(*region))
> > return -EINVAL;
> >
> > private = dev_get_drvdata(mdev_parent_dev(mdev));
> > - if (private->state != VFIO_CCW_STATE_IDLE)
> > + if (private->state == VFIO_CCW_STATE_NOT_OPER ||
> > + private->state == VFIO_CCW_STATE_STANDBY)
> > return -EACCES;
> > + if (!mutex_trylock(&private->io_mutex))
> > + return -EAGAIN;
> >
> > region = private->io_region;
> > - if (copy_from_user((void *)region + *ppos, buf, count))
> > - return -EFAULT;
> > + if (copy_from_user((void *)region + *ppos, buf, count)) {
>
> This might race with vfio_ccw_sch_io_todo() on
> private->io_region->irb_area, or?
Ah yes, this should also take the mutex (should work because we're on a
workqueue).
>
> > + ret = -EFAULT;
> > + goto out_unlock;
> > + }
> >
> > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);
> > - if (region->ret_code != 0) {
> > - private->state = VFIO_CCW_STATE_IDLE;
> > - return region->ret_code;
> > - }
> > + ret = (region->ret_code != 0) ? region->ret_code : count;
> >
> > - return count;
> > +out_unlock:
> > + mutex_unlock(&private->io_mutex);
> > + return ret;
> > }
> >
> [..]
>
next prev parent reply other threads:[~2019-01-22 10:29 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-21 11:03 [PATCH v2 0/5] vfio-ccw: support hsch/csch (kernel part) Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-21 11:03 ` [PATCH v2 1/5] vfio-ccw: make it safe to access channel programs Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-22 14:56 ` Halil Pasic
2019-01-22 14:56 ` [Qemu-devel] " Halil Pasic
2019-01-22 15:19 ` Cornelia Huck
2019-01-22 15:19 ` [Qemu-devel] " Cornelia Huck
2019-01-21 11:03 ` [PATCH v2 2/5] vfio-ccw: concurrent I/O handling Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-21 20:20 ` Halil Pasic
2019-01-21 20:20 ` [Qemu-devel] " Halil Pasic
2019-01-22 10:29 ` Cornelia Huck [this message]
2019-01-22 10:29 ` Cornelia Huck
2019-01-22 11:17 ` Halil Pasic
2019-01-22 11:17 ` [Qemu-devel] " Halil Pasic
2019-01-22 11:53 ` Cornelia Huck
2019-01-22 11:53 ` [Qemu-devel] " Cornelia Huck
2019-01-22 12:46 ` Halil Pasic
2019-01-22 12:46 ` [Qemu-devel] " Halil Pasic
2019-01-22 17:26 ` Cornelia Huck
2019-01-22 17:26 ` [Qemu-devel] " Cornelia Huck
2019-01-22 19:03 ` Halil Pasic
2019-01-22 19:03 ` [Qemu-devel] " Halil Pasic
2019-01-23 10:34 ` Cornelia Huck
2019-01-23 10:34 ` [Qemu-devel] " Cornelia Huck
2019-01-23 13:06 ` Halil Pasic
2019-01-23 13:06 ` [Qemu-devel] " Halil Pasic
2019-01-23 13:34 ` Cornelia Huck
2019-01-23 13:34 ` [Qemu-devel] " Cornelia Huck
2019-01-24 19:16 ` Eric Farman
2019-01-24 19:16 ` [Qemu-devel] " Eric Farman
2019-01-25 10:13 ` Cornelia Huck
2019-01-25 10:13 ` [Qemu-devel] " Cornelia Huck
2019-01-22 18:33 ` Halil Pasic
2019-01-22 18:33 ` [Qemu-devel] " Halil Pasic
2019-01-23 10:21 ` Cornelia Huck
2019-01-23 10:21 ` [Qemu-devel] " Cornelia Huck
2019-01-23 13:30 ` Halil Pasic
2019-01-23 13:30 ` [Qemu-devel] " Halil Pasic
2019-01-24 10:05 ` Cornelia Huck
2019-01-24 10:05 ` [Qemu-devel] " Cornelia Huck
2019-01-24 10:08 ` Pierre Morel
2019-01-24 10:08 ` [Qemu-devel] " Pierre Morel
2019-01-24 10:19 ` Cornelia Huck
2019-01-24 10:19 ` [Qemu-devel] " Cornelia Huck
2019-01-24 11:18 ` Pierre Morel
2019-01-24 11:18 ` [Qemu-devel] " Pierre Morel
2019-01-24 11:45 ` Halil Pasic
2019-01-24 11:45 ` [Qemu-devel] " Halil Pasic
2019-01-24 19:14 ` Eric Farman
2019-01-24 19:14 ` [Qemu-devel] " Eric Farman
2019-01-25 2:25 ` Eric Farman
2019-01-25 2:25 ` [Qemu-devel] " Eric Farman
2019-01-25 2:37 ` Eric Farman
2019-01-25 2:37 ` [Qemu-devel] " Eric Farman
2019-01-25 10:24 ` Cornelia Huck
2019-01-25 10:24 ` [Qemu-devel] " Cornelia Huck
2019-01-25 12:58 ` Cornelia Huck
2019-01-25 12:58 ` [Qemu-devel] " Cornelia Huck
2019-01-25 14:01 ` Halil Pasic
2019-01-25 14:01 ` [Qemu-devel] " Halil Pasic
2019-01-25 14:21 ` Cornelia Huck
2019-01-25 14:21 ` [Qemu-devel] " Cornelia Huck
2019-01-25 16:04 ` Halil Pasic
2019-01-25 16:04 ` [Qemu-devel] " Halil Pasic
2019-01-28 17:13 ` Cornelia Huck
2019-01-28 17:13 ` [Qemu-devel] " Cornelia Huck
2019-01-28 19:30 ` Halil Pasic
2019-01-28 19:30 ` [Qemu-devel] " Halil Pasic
2019-01-29 9:58 ` Cornelia Huck
2019-01-29 9:58 ` [Qemu-devel] " Cornelia Huck
2019-01-29 19:39 ` Halil Pasic
2019-01-29 19:39 ` [Qemu-devel] " Halil Pasic
2019-01-30 13:29 ` Cornelia Huck
2019-01-30 13:29 ` [Qemu-devel] " Cornelia Huck
2019-01-30 14:32 ` Farhan Ali
2019-01-30 14:32 ` [Qemu-devel] " Farhan Ali
2019-01-28 17:09 ` Cornelia Huck
2019-01-28 17:09 ` [Qemu-devel] " Cornelia Huck
2019-01-28 19:15 ` Halil Pasic
2019-01-28 19:15 ` [Qemu-devel] " Halil Pasic
2019-01-28 21:48 ` Eric Farman
2019-01-28 21:48 ` [Qemu-devel] " Eric Farman
2019-01-29 10:20 ` Cornelia Huck
2019-01-29 10:20 ` [Qemu-devel] " Cornelia Huck
2019-01-29 14:14 ` Eric Farman
2019-01-29 14:14 ` [Qemu-devel] " Eric Farman
2019-01-29 18:53 ` Cornelia Huck
2019-01-29 18:53 ` [Qemu-devel] " Cornelia Huck
2019-01-29 10:10 ` Cornelia Huck
2019-01-29 10:10 ` [Qemu-devel] " Cornelia Huck
2019-01-25 15:57 ` Eric Farman
2019-01-25 15:57 ` [Qemu-devel] " Eric Farman
2019-01-28 17:24 ` Cornelia Huck
2019-01-28 17:24 ` [Qemu-devel] " Cornelia Huck
2019-01-28 21:50 ` Eric Farman
2019-01-28 21:50 ` [Qemu-devel] " Eric Farman
2019-01-25 20:22 ` Eric Farman
2019-01-25 20:22 ` [Qemu-devel] " Eric Farman
2019-01-28 17:31 ` Cornelia Huck
2019-01-28 17:31 ` [Qemu-devel] " Cornelia Huck
2019-01-25 13:09 ` Halil Pasic
2019-01-25 13:09 ` [Qemu-devel] " Halil Pasic
2019-01-25 12:58 ` Halil Pasic
2019-01-25 12:58 ` [Qemu-devel] " Halil Pasic
2019-01-25 20:21 ` Eric Farman
2019-01-25 20:21 ` [Qemu-devel] " Eric Farman
2019-01-21 11:03 ` [PATCH v2 3/5] vfio-ccw: add capabilities chain Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-23 15:57 ` [qemu-s390x] " Halil Pasic
2019-01-23 15:57 ` [Qemu-devel] " Halil Pasic
2019-01-25 16:19 ` Eric Farman
2019-01-25 16:19 ` [Qemu-devel] " Eric Farman
2019-01-25 21:00 ` Eric Farman
2019-01-25 21:00 ` [Qemu-devel] " Eric Farman
2019-01-28 17:34 ` Cornelia Huck
2019-01-28 17:34 ` [Qemu-devel] " Cornelia Huck
2019-01-21 11:03 ` [PATCH v2 4/5] s390/cio: export hsch to modules Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-22 15:21 ` [qemu-s390x] " Halil Pasic
2019-01-22 15:21 ` [Qemu-devel] " Halil Pasic
2019-01-21 11:03 ` [PATCH v2 5/5] vfio-ccw: add handling for async channel instructions Cornelia Huck
2019-01-21 11:03 ` [Qemu-devel] " Cornelia Huck
2019-01-23 15:51 ` Halil Pasic
2019-01-23 15:51 ` [Qemu-devel] " Halil Pasic
2019-01-24 10:06 ` Cornelia Huck
2019-01-24 10:06 ` [Qemu-devel] " Cornelia Huck
2019-01-24 10:37 ` Halil Pasic
2019-01-24 10:37 ` [Qemu-devel] " Halil Pasic
2019-01-25 21:00 ` Eric Farman
2019-01-25 21:00 ` [Qemu-devel] " Eric Farman
2019-01-28 17:40 ` Cornelia Huck
2019-01-28 17:40 ` [Qemu-devel] " Cornelia Huck
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