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Date: Wed, 5 Jan 2022 11:05:24 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com
Subject: Re: [RFC PATCH v2 1/6] remoteproc: core: Introduce virtio device
add/remove functions
On Wed, Jan 05, 2022 at 09:05:21AM +0100, Arnaud POULIQUEN wrote:
> Hello Mathieu,
>
> On 1/4/22 8:08 PM, Mathieu Poirier wrote:
> > Good morning,
> >
> > On Wed, Dec 22, 2021 at 09:23:44AM +0100, Arnaud Pouliquen wrote:
> > > In preparation of the migration of the management of rvdev in
> > > remoteproc_virtio.c, this patch spins off new functions to manage the
> > > remoteproc virtio device.
> > >
> > > The rproc_rvdev_add_device and rproc_rvdev_remove_device will be
> > > moved to remoteproc_virtio.c.
> > >
> > > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> > > ---
> > > update vs previous revision:
> > > - update according to the rebase from v15-rc1 to v16-rc1
> > > - split patch to introduce rproc_register_rvdev and rproc_unregister_rvdev
> > > function in a separate patch
> > > ---
> > > drivers/remoteproc/remoteproc_core.c | 94 +++++++++++++++++-----------
> > > 1 file changed, 57 insertions(+), 37 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> > > index 69f51acf235e..d1f1c5c25bd7 100644
> > > --- a/drivers/remoteproc/remoteproc_core.c
> > > +++ b/drivers/remoteproc/remoteproc_core.c
> > > @@ -484,6 +484,61 @@ static int copy_dma_range_map(struct device *to, struct device *from)
> > > return 0;
> > > }
> > > +static int rproc_rvdev_add_device(struct rproc_vdev *rvdev)
> > > +{
> > > + struct rproc *rproc = rvdev->rproc;
> > > + char name[16];
> > > + int ret;
> > > +
> > > + snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
> > > + rvdev->dev.parent = &rproc->dev;
> > > + rvdev->dev.release = rproc_rvdev_release;
> > > + dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
> > > + dev_set_drvdata(&rvdev->dev, rvdev);
> > > +
> > > + ret = device_register(&rvdev->dev);
> > > + if (ret) {
> > > + put_device(&rvdev->dev);
> > > + return ret;
> > > + }
> >
> > Registering the device here is a problem... If device_register() fails
> > put_device() is called and we return, only to call device_unregister() on the
> > same device in rproc_handle_vdev().
> >
> > Moreover in rproc_handle_vdev(), device_unregister() is called in the error
> > path but device_register() is called here in rproc_rvdev_add_device(). This
> > introduces coupling between the two functions, making it hard to maintain from
> > hereon.
>
> Very relevant, I need to rework the error management.
>
> >
> > I suggest calling device_register() in rproc_handle_vdev() after
> > rproc_rvdev_add_device() has returned successfully.
>
> One of the goals of this patchset is to move the device_register in
> remote_proc_virtio.c
> Doing this would not go in this direction.
>
> I need to test but following could be an alternative:
> - Call rproc_rvdev_remove_device in rproc_handle_vdev in case of error.
> - Remove the put_device in rproc_rvdev_add_device.
>
Right, some kind of rework is needed. I offered a simple solution but something
more involved is likely required.
> => This would be aligned with patch [6/6] implementation
> with rproc_virtio_register_device/rproc_virtio_unregister_device...
>
> Thanks,
> Arnaud
>
> >
> > More comments to come tomorrow.
> >
> > Thanks,
> > Mathieu
> >
> > > + ret = copy_dma_range_map(&rvdev->dev, rproc->dev.parent);
> > > + if (ret)
> > > + goto free_rvdev;
> > > +
> > > + /* Make device dma capable by inheriting from parent's capabilities */
> > > + set_dma_ops(&rvdev->dev, get_dma_ops(rproc->dev.parent));
> > > +
> > > + ret = dma_coerce_mask_and_coherent(&rvdev->dev,
> > > + dma_get_mask(rproc->dev.parent));
> > > + if (ret) {
> > > + dev_warn(&rvdev->dev,
> > > + "Failed to set DMA mask %llx. Trying to continue... (%pe)\n",
> > > + dma_get_mask(rproc->dev.parent), ERR_PTR(ret));
> > > + }
> > > +
> > > + list_add_tail(&rvdev->node, &rproc->rvdevs);
> > > +
> > > + rvdev->subdev.start = rproc_vdev_do_start;
> > > + rvdev->subdev.stop = rproc_vdev_do_stop;
> > > +
> > > + rproc_add_subdev(rproc, &rvdev->subdev);
> > > +
> > > + return 0;
> > > +
> > > +free_rvdev:
> > > + device_unregister(&rvdev->dev);
> > > + return ret;
> > > +}
> > > +
> > > +static void rproc_rvdev_remove_device(struct rproc_vdev *rvdev)
> > > +{
> > > + struct rproc *rproc = rvdev->rproc;
> > > +
> > > + rproc_remove_subdev(rproc, &rvdev->subdev);
> > > + list_del(&rvdev->node);
> > > + device_unregister(&rvdev->dev);
> > > +}
> > > +
> > > /**
> > > * rproc_handle_vdev() - handle a vdev fw resource
> > > * @rproc: the remote processor
> > > @@ -519,7 +574,6 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> > > struct device *dev = &rproc->dev;
> > > struct rproc_vdev *rvdev;
> > > int i, ret;
> > > - char name[16];
> > > /* make sure resource isn't truncated */
> > > if (struct_size(rsc, vring, rsc->num_of_vrings) + rsc->config_len >
> > > @@ -553,34 +607,10 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> > > rvdev->rproc = rproc;
> > > rvdev->index = rproc->nb_vdev++;
> > > - /* Initialise vdev subdevice */
> > > - snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
> > > - rvdev->dev.parent = &rproc->dev;
> > > - rvdev->dev.release = rproc_rvdev_release;
> > > - dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
> > > - dev_set_drvdata(&rvdev->dev, rvdev);
> > > -
> > > - ret = device_register(&rvdev->dev);
> > > - if (ret) {
> > > - put_device(&rvdev->dev);
> > > - return ret;
> > > - }
> > > -
> > > - ret = copy_dma_range_map(&rvdev->dev, rproc->dev.parent);
> > > + ret = rproc_rvdev_add_device(rvdev);
> > > if (ret)
> > > goto free_rvdev;
> > > - /* Make device dma capable by inheriting from parent's capabilities */
> > > - set_dma_ops(&rvdev->dev, get_dma_ops(rproc->dev.parent));
> > > -
> > > - ret = dma_coerce_mask_and_coherent(&rvdev->dev,
> > > - dma_get_mask(rproc->dev.parent));
> > > - if (ret) {
> > > - dev_warn(dev,
> > > - "Failed to set DMA mask %llx. Trying to continue... (%pe)\n",
> > > - dma_get_mask(rproc->dev.parent), ERR_PTR(ret));
> > > - }
> > > -
> > > /* parse the vrings */
> > > for (i = 0; i < rsc->num_of_vrings; i++) {
> > > ret = rproc_parse_vring(rvdev, rsc, i);
> > > @@ -598,13 +628,6 @@ static int rproc_handle_vdev(struct rproc *rproc, void *ptr,
> > > goto unwind_vring_allocations;
> > > }
> > > - list_add_tail(&rvdev->node, &rproc->rvdevs);
> > > -
> > > - rvdev->subdev.start = rproc_vdev_do_start;
> > > - rvdev->subdev.stop = rproc_vdev_do_stop;
> > > -
> > > - rproc_add_subdev(rproc, &rvdev->subdev);
> > > -
> > > return 0;
> > > unwind_vring_allocations:
> > > @@ -619,7 +642,6 @@ void rproc_vdev_release(struct kref *ref)
> > > {
> > > struct rproc_vdev *rvdev = container_of(ref, struct rproc_vdev, refcount);
> > > struct rproc_vring *rvring;
> > > - struct rproc *rproc = rvdev->rproc;
> > > int id;
> > > for (id = 0; id < ARRAY_SIZE(rvdev->vring); id++) {
> > > @@ -627,9 +649,7 @@ void rproc_vdev_release(struct kref *ref)
> > > rproc_free_vring(rvring);
> > > }
> > > - rproc_remove_subdev(rproc, &rvdev->subdev);
> > > - list_del(&rvdev->node);
> > > - device_unregister(&rvdev->dev);
> > > + rproc_rvdev_remove_device(rvdev);
> > > }
> > > /**
> > > --
> > > 2.17.1
> > >
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