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Date: Tue, 4 Jan 2022 12:08:10 -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
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.
I suggest calling device_register() in rproc_handle_vdev() after
rproc_rvdev_add_device() has returned successfully.
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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