On Thu, Jun 18, 2026 at 02:27:22PM +0100, Rodrigo Alencar via B4 Relay wrote:
> From: Rodrigo Alencar <[email protected]>
>
> Move logic to create a channel prefix for naming attribute files into a
> separate __iio_chan_prefix_emit() function for reuse.
>
> Signed-off-by: Rodrigo Alencar <[email protected]>
> ---
> drivers/iio/industrialio-core.c | 167
> ++++++++++++++++------------------------
> 1 file changed, 68 insertions(+), 99 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 03019bf9327b..9373006235c8 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -26,6 +26,7 @@
> #include <linux/property.h>
> #include <linux/sched.h>
> #include <linux/slab.h>
> +#include <linux/sprintf.h>
> #include <linux/wait.h>
>
> #include <linux/iio/buffer.h>
> @@ -199,6 +200,64 @@ static const char * const iio_chan_info_postfix[] = {
> [IIO_CHAN_INFO_CONVDELAY] = "convdelay",
> [IIO_CHAN_INFO_POWERFACTOR] = "powerfactor",
> };
> +
> +static int __iio_chan_prefix_emit(const struct iio_chan_spec *chan,
> + enum iio_shared_by shared_by,
> + char *buf, size_t len)
> +{
> + const char *dir = iio_direction[chan->output];
> + const char *type = iio_chan_type_name_spec[chan->type];
> + int n = 0;
> +
> + switch (shared_by) {
> + case IIO_SHARED_BY_ALL:
> + buf[0] = '\0'; /* empty channel prefix */
> + break;
> + case IIO_SHARED_BY_DIR:
> + n = scnprintf(buf, len, "%s", dir);
> + break;
> + case IIO_SHARED_BY_TYPE:
> + n = scnprintf(buf, len, "%s_%s", dir, type);
> + if (chan->differential)
> + n += scnprintf(buf + n, len - n, "-%s", type);
> + break;
> + case IIO_SEPARATE:
> + if (chan->indexed) {
> + n = scnprintf(buf, len, "%s_%s%d", dir, type,
> + chan->channel);
> + if (chan->differential)
> + n += scnprintf(buf + n, len - n, "-%s%d", type,
> + chan->channel2);
> + } else {
> + if (chan->differential) {
> + WARN(1, "Differential channels must be
> indexed\n");
> + return -EINVAL;
> + }
> + n = scnprintf(buf, len, "%s_%s", dir, type);
> + }
> +
> + if (chan->modified) {
> + if (chan->differential) {
> + WARN(1, "Differential channels can not have
> modifier\n");
> + return -EINVAL;
WARN() looks too much to me. dev_error() as we're treating it as such. I
guess you don't want to pass struct device but not really an issue IMHO.
> + }
> + n += scnprintf(buf + n, len - n, "_%s",
> + iio_modifier_names[chan->channel2]);
> + }
> +
> + if (chan->extend_name)
> + n += scnprintf(buf + n, len - n, "_%s",
> chan->extend_name);
> + break;
> + }
> +
> + if (n > 0 && n < len - 1) { /* prefix termination if not empty */
> + buf[n++] = '_';
> + buf[n] = '\0';
> + }
> +
Can't we handle the above in the caller on kasprintf()? Then we could
simplify and return in place.
> + return n;
> +}
> +
> /**
> * iio_device_id() - query the unique ID for the device
> * @indio_dev: Device structure whose ID is being queried
> @@ -1100,106 +1159,19 @@ int __iio_device_attr_init(struct device_attribute
> *dev_attr,
> size_t len),
> enum iio_shared_by shared_by)
> {
> - int ret = 0;
> - char *name = NULL;
> - char *full_postfix;
> + char prefix[NAME_MAX + 1];
> + int ret;
>
> sysfs_attr_init(&dev_attr->attr);
>
> - /* Build up postfix of <extend_name>_<modifier>_postfix */
> - if (chan->modified && (shared_by == IIO_SEPARATE)) {
> - if (chan->extend_name)
> - full_postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
> -
> iio_modifier_names[chan->channel2],
> - chan->extend_name,
> - postfix);
> - else
> - full_postfix = kasprintf(GFP_KERNEL, "%s_%s",
> -
> iio_modifier_names[chan->channel2],
> - postfix);
> - } else {
> - if (chan->extend_name == NULL || shared_by != IIO_SEPARATE)
> - full_postfix = kstrdup(postfix, GFP_KERNEL);
> - else
> - full_postfix = kasprintf(GFP_KERNEL,
> - "%s_%s",
> - chan->extend_name,
> - postfix);
> - }
> - if (full_postfix == NULL)
> + ret = __iio_chan_prefix_emit(chan, shared_by, prefix, sizeof(prefix));
> + if (ret < 0)
> + return ret;
> +
> + dev_attr->attr.name = kasprintf(GFP_KERNEL, "%s%s", prefix, postfix);
> + if (!dev_attr->attr.name)
> return -ENOMEM;
I don't oppose the change. Looks like a nice cleanup. But bear in mind
this very sensible as any subtle mistake means ABI breakage.
- Nuno Sá
>
> - if (chan->differential) { /* Differential can not have modifier */
> - switch (shared_by) {
> - case IIO_SHARED_BY_ALL:
> - name = kasprintf(GFP_KERNEL, "%s", full_postfix);
> - break;
> - case IIO_SHARED_BY_DIR:
> - name = kasprintf(GFP_KERNEL, "%s_%s",
> - iio_direction[chan->output],
> - full_postfix);
> - break;
> - case IIO_SHARED_BY_TYPE:
> - name = kasprintf(GFP_KERNEL, "%s_%s-%s_%s",
> - iio_direction[chan->output],
> - iio_chan_type_name_spec[chan->type],
> - iio_chan_type_name_spec[chan->type],
> - full_postfix);
> - break;
> - case IIO_SEPARATE:
> - if (!chan->indexed) {
> - WARN(1, "Differential channels must be
> indexed\n");
> - ret = -EINVAL;
> - goto error_free_full_postfix;
> - }
> - name = kasprintf(GFP_KERNEL,
> - "%s_%s%d-%s%d_%s",
> - iio_direction[chan->output],
> - iio_chan_type_name_spec[chan->type],
> - chan->channel,
> - iio_chan_type_name_spec[chan->type],
> - chan->channel2,
> - full_postfix);
> - break;
> - }
> - } else { /* Single ended */
> - switch (shared_by) {
> - case IIO_SHARED_BY_ALL:
> - name = kasprintf(GFP_KERNEL, "%s", full_postfix);
> - break;
> - case IIO_SHARED_BY_DIR:
> - name = kasprintf(GFP_KERNEL, "%s_%s",
> - iio_direction[chan->output],
> - full_postfix);
> - break;
> - case IIO_SHARED_BY_TYPE:
> - name = kasprintf(GFP_KERNEL, "%s_%s_%s",
> - iio_direction[chan->output],
> - iio_chan_type_name_spec[chan->type],
> - full_postfix);
> - break;
> -
> - case IIO_SEPARATE:
> - if (chan->indexed)
> - name = kasprintf(GFP_KERNEL, "%s_%s%d_%s",
> - iio_direction[chan->output],
> -
> iio_chan_type_name_spec[chan->type],
> - chan->channel,
> - full_postfix);
> - else
> - name = kasprintf(GFP_KERNEL, "%s_%s_%s",
> - iio_direction[chan->output],
> -
> iio_chan_type_name_spec[chan->type],
> - full_postfix);
> - break;
> - }
> - }
> - if (name == NULL) {
> - ret = -ENOMEM;
> - goto error_free_full_postfix;
> - }
> - dev_attr->attr.name = name;
> -
> if (readfunc) {
> dev_attr->attr.mode |= 0444;
> dev_attr->show = readfunc;
> @@ -1210,10 +1182,7 @@ int __iio_device_attr_init(struct device_attribute
> *dev_attr,
> dev_attr->store = writefunc;
> }
>
> -error_free_full_postfix:
> - kfree(full_postfix);
> -
> - return ret;
> + return 0;
> }
>
> static void __iio_device_attr_deinit(struct device_attribute *dev_attr)
>
> --
> 2.43.0
>
>
