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SubjectRe: [PATCH v3 04/11] iio: core: rework iio device group creation
On Mon, 1 Feb 2021 16:50:58 +0200
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> Up until now, the device groups that an IIO device had were limited to 6.
> Two of these groups would account for buffer attributes (the buffer/ and
> scan_elements/ directories).
>
> Since we want to add multiple buffers per IIO device, this number may not
> be enough, when adding a second buffer. So, this change reallocates the
> groups array whenever an IIO device group is added, via a
> iio_device_register_sysfs_group() helper.
>
> This also means that the groups array should be assigned to
> 'indio_dev.dev.groups' really late, right before {cdev_}device_add() is
> called to do the entire setup.
> And we also must take care to free this array when the sysfs resources are
> being cleaned up.
>
> With this change we can also move the 'groups' & 'groupcounter' fields to
> the iio_dev_opaque object. Up until now, this didn't make a whole lot of
> sense (especially since we weren't sure how multibuffer support would look
> like in the end).
> But doing it now kills one birds with one stone.
>
> An alternative, would be to add a configurable Kconfig symbol
> CONFIG_IIO_MAX_BUFFERS_PER_DEVICE (or something like that) and compute a
> static maximum of the groups we can support per IIO device. But that would
> probably annoy a few people since that would make the system less
> configurable.
>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Nice change irrespective of the rest of the series needing it.

Few comments below.

Jonathan

> ---
> drivers/iio/iio_core.h | 3 +++
> drivers/iio/industrialio-buffer.c | 12 +++++++++--
> drivers/iio/industrialio-core.c | 32 +++++++++++++++++++++++++++---
> drivers/iio/industrialio-event.c | 5 ++++-
> drivers/iio/industrialio-trigger.c | 6 ++----
> include/linux/iio/iio-opaque.h | 4 ++++
> include/linux/iio/iio.h | 5 -----
> 7 files changed, 52 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
> index fced02cadcc3..7d5b179c1fe7 100644
> --- a/drivers/iio/iio_core.h
> +++ b/drivers/iio/iio_core.h
> @@ -46,6 +46,9 @@ int __iio_add_chan_devattr(const char *postfix,
> struct list_head *attr_list);
> void iio_free_chan_devattr_list(struct list_head *attr_list);
>
> +int iio_device_register_sysfs_group(struct iio_dev *indio_dev,
> + const struct attribute_group *group);
> +
> ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals);
>
> /* Event interface flags */
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index 2f7426a2f47c..cc846988fdb9 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -1287,7 +1287,9 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
> buffer->buffer_group.name = "buffer";
> buffer->buffer_group.attrs = attr;
>
> - indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
> + ret = iio_device_register_sysfs_group(indio_dev, &buffer->buffer_group);
> + if (ret)
> + goto error_free_buffer_attrs;
>
> attrcount = 0;
> INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
> @@ -1330,14 +1332,20 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
>
> list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
> buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
> - indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
> +
> + ret = iio_device_register_sysfs_group(indio_dev, &buffer->scan_el_group);
> + if (ret)
> + goto error_free_scan_el_attrs;
>
> return 0;
>
> +error_free_scan_el_attrs:
> + kfree(buffer->scan_el_group.attrs);
> error_free_scan_mask:
> bitmap_free(buffer->scan_mask);
> error_cleanup_dynamic:
> iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> +error_free_buffer_attrs:
> kfree(buffer->buffer_group.attrs);
>
> return ret;
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 0a6fd299a978..ccd7aaff6d13 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1452,6 +1452,25 @@ static ssize_t iio_store_timestamp_clock(struct device *dev,
> return len;
> }
>
> +int iio_device_register_sysfs_group(struct iio_dev *indio_dev,
> + const struct attribute_group *group)
> +{
> + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
> + const struct attribute_group **new, **old = iio_dev_opaque->groups;
> + unsigned int cnt = iio_dev_opaque->groupcounter;
> +
> + new = krealloc(old, sizeof(*new) * (cnt + 2), GFP_KERNEL);
> + if (!new)
> + return -ENOMEM;
> +
> + new[iio_dev_opaque->groupcounter++] = group;
> + new[iio_dev_opaque->groupcounter] = NULL;
> +
> + iio_dev_opaque->groups = new;
> +
> + return 0;
> +}
> +
> static DEVICE_ATTR(current_timestamp_clock, S_IRUGO | S_IWUSR,
> iio_show_timestamp_clock, iio_store_timestamp_clock);
>
> @@ -1525,8 +1544,10 @@ static int iio_device_register_sysfs(struct iio_dev *indio_dev)
> if (clk)
> iio_dev_opaque->chan_attr_group.attrs[attrn++] = clk;
>
> - indio_dev->groups[indio_dev->groupcounter++] =
> - &iio_dev_opaque->chan_attr_group;
> + ret = iio_device_register_sysfs_group(indio_dev,
> + &iio_dev_opaque->chan_attr_group);
> + if (ret)
> + goto error_clear_attrs;
>
> return 0;
>
> @@ -1543,6 +1564,9 @@ static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
> iio_free_chan_devattr_list(&iio_dev_opaque->channel_attr_list);
> kfree(iio_dev_opaque->chan_attr_group.attrs);
> iio_dev_opaque->chan_attr_group.attrs = NULL;
> + kfree(iio_dev_opaque->groups);
> + iio_dev_opaque->groups = NULL;
I can see you are matching style above, but right now I can't see why
we set chan_attr_group.attrs = NULL
or this new case.

> + iio_dev_opaque->groupcounter = 0;

or indeed groupcounter.

> }
>
> static void iio_dev_release(struct device *device)
> @@ -1592,7 +1616,6 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
> ALIGN(sizeof(struct iio_dev_opaque), IIO_ALIGN);
>
> dev->dev.parent = parent;
> - dev->dev.groups = dev->groups;

Hohum. Nothing to do with this patch but not sure why the iio_dev is called dev here...
I (or someone else) should fix that at somepoint after this is in place as it confused me.


> dev->dev.type = &iio_device_type;
> dev->dev.bus = &iio_bus_type;
> device_initialize(&dev->dev);
> @@ -1853,6 +1876,9 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
> indio_dev->chrdev.owner = this_mod;
> }
>
> + /* assign device groups now; they should be all registered now */
> + indio_dev->dev.groups = iio_dev_opaque->groups;
> +
> ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
> if (ret < 0)
> goto error_unreg_eventset;
> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index 7e532117ac55..ea8947cc21e4 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -544,7 +544,10 @@ int iio_device_register_eventset(struct iio_dev *indio_dev)
> /* Add all elements from the list. */
> list_for_each_entry(p, &ev_int->dev_attr_list, l)
> ev_int->group.attrs[attrn++] = &p->dev_attr.attr;
> - indio_dev->groups[indio_dev->groupcounter++] = &ev_int->group;
> +
> + ret = iio_device_register_sysfs_group(indio_dev, &ev_int->group);
> + if (ret)
> + goto error_free_setup_event_lines;
>
> ev_int->ioctl_handler.ioctl = iio_event_ioctl;
> iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev,
> diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
> index 438d5012e8b8..a035d5c2a445 100644
> --- a/drivers/iio/industrialio-trigger.c
> +++ b/drivers/iio/industrialio-trigger.c
> @@ -694,10 +694,8 @@ EXPORT_SYMBOL(iio_trigger_validate_own_device);
>
> int iio_device_register_trigger_consumer(struct iio_dev *indio_dev)
> {
> - indio_dev->groups[indio_dev->groupcounter++] =
> - &iio_trigger_consumer_attr_group;
> -
> - return 0;
> + return iio_device_register_sysfs_group(indio_dev,
> + &iio_trigger_consumer_attr_group);
> }
>
> void iio_device_unregister_trigger_consumer(struct iio_dev *indio_dev)
> diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h
> index 07c5a8e52ca8..8ba13a5c7af6 100644
> --- a/include/linux/iio/iio-opaque.h
> +++ b/include/linux/iio/iio-opaque.h
> @@ -12,6 +12,8 @@
> * attributes
> * @chan_attr_group: group for all attrs in base directory
> * @ioctl_handlers: ioctl handlers registered with the core handler
> + * @groups: attribute groups
> + * @groupcounter: index of next attribute group
> * @debugfs_dentry: device specific debugfs dentry
> * @cached_reg_addr: cached register address for debugfs reads
> * @read_buf: read buffer to be used for the initial reg read
> @@ -24,6 +26,8 @@ struct iio_dev_opaque {
> struct list_head channel_attr_list;
> struct attribute_group chan_attr_group;
> struct list_head ioctl_handlers;
> + const struct attribute_group **groups;
> + int groupcounter;
> #if defined(CONFIG_DEBUG_FS)
> struct dentry *debugfs_dentry;
> unsigned cached_reg_addr;
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index e4a9822e6495..f8585d01fc76 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -518,8 +518,6 @@ struct iio_buffer_setup_ops {
> * @setup_ops: [DRIVER] callbacks to call before and after buffer
> * enable/disable
> * @chrdev: [INTERN] associated character device
> - * @groups: [INTERN] attribute groups
> - * @groupcounter: [INTERN] index of next attribute group
> * @flags: [INTERN] file ops related flags including busy flag.
> * @priv: [DRIVER] reference to driver's private information
> * **MUST** be accessed **ONLY** via iio_priv() helper
> @@ -556,9 +554,6 @@ struct iio_dev {
> struct mutex info_exist_lock;
> const struct iio_buffer_setup_ops *setup_ops;
> struct cdev chrdev;
> -#define IIO_MAX_GROUPS 6
> - const struct attribute_group *groups[IIO_MAX_GROUPS + 1];
> - int groupcounter;
>
> unsigned long flags;
> void *priv;

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