Messages in this thread | | | Subject | Re: [PATCH v5 1/5] counter: Internalize sysfs interface code | From | David Lechner <> | Date | Mon, 12 Oct 2020 21:15:00 -0500 |
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On 9/26/20 9:18 PM, William Breathitt Gray wrote: > This is a reimplementation of the Generic Counter driver interface.
I'll follow up if I find any problems while testing but here are some comments I had from looking over the patch.
> diff --git a/drivers/counter/counter-core.c b/drivers/counter/counter-core.c > new file mode 100644 > index 000000000000..987c6e8277eb > --- /dev/null > +++ b/drivers/counter/counter-core.c
> +/** > + * counter_register - register Counter to the system > + * @counter: pointer to Counter to register > + * > + * This function registers a Counter to the system. A sysfs "counter" directory > + * will be created and populated with sysfs attributes correlating with the > + * Counter Signals, Synapses, and Counts respectively. > + */ > +int counter_register(struct counter_device *const counter) > +{ > + struct device *const dev = &counter->dev; > + int err; > + > + /* Acquire unique ID */ > + counter->id = ida_simple_get(&counter_ida, 0, 0, GFP_KERNEL); > + if (counter->id < 0) > + return counter->id; > + > + /* Configure device structure for Counter */ > + dev->type = &counter_device_type; > + dev->bus = &counter_bus_type; > + if (counter->parent) { > + dev->parent = counter->parent; > + dev->of_node = counter->parent->of_node; > + } > + dev_set_name(dev, "counter%d", counter->id); > + device_initialize(dev);> + dev_set_drvdata(dev, counter); > + > + /* Add Counter sysfs attributes */ > + err = counter_sysfs_add(counter); > + if (err) > + goto err_free_id; > + > + /* Add device to system */ > + err = device_add(dev); > + if (err) { > + put_device(dev); > + goto err_free_id; > + } > + > + return 0; > + > +err_free_id: > + /* get_device/put_device combo used to free managed resources */ > + get_device(dev); > + put_device(dev);
I've never seen this in a driver before, so it makes me think this is not the "right way" to do this. After device_initialize() is called, we already should have a reference to dev, so only device_put() is needed.
> + ida_simple_remove(&counter_ida, counter->id);
In the case of error after device_initialize() is called, won't this result in ida_simple_remove() being called twice, once here and once in the release callback?
> + return err; > +} > +EXPORT_SYMBOL_GPL(counter_register); > + > +/** > + * counter_unregister - unregister Counter from the system > + * @counter: pointer to Counter to unregister > + * > + * The Counter is unregistered from the system; all allocated memory is freed. > + */ > +void counter_unregister(struct counter_device *const counter) > +{ > + if (!counter) > + return; > + > + device_unregister(&counter->dev); > +} > +EXPORT_SYMBOL_GPL(counter_unregister); > + > +static void devm_counter_unreg(struct device *dev, void *res)
To be consistent, it would be nice to spell out unregister.
> +{ > + counter_unregister(*(struct counter_device **)res); > +} > +
> diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c > new file mode 100644 > index 000000000000..e66ed99dd5ea > --- /dev/null > +++ b/drivers/counter/counter-sysfs.c
> +/** > + * counter_sysfs_add - Adds Counter sysfs attributes to the device structure > + * @counter: Pointer to the Counter device structure > + * > + * Counter sysfs attributes are created and added to the respective device > + * structure for later registration to the system. Resource-managed memory > + * allocation is performed by this function, and this memory should be freed > + * when no longer needed (automatically by a device_unregister call, or > + * manually by a devres_release_all call). > + */ > +int counter_sysfs_add(struct counter_device *const counter) > +{ > + struct device *const dev = &counter->dev; > + const size_t num_groups = counter->num_signals + counter->num_counts + > + 1;
It is OK to go past 80 columns, especially for just for a few characters.
> + struct counter_attribute_group *groups; > + size_t i, j; > + int err; > + struct attribute_group *group; > + struct counter_attribute *p; > + > + /* Allocate space for attribute groups (signals, counts, and ext) */ > + groups = devm_kcalloc(dev, num_groups, sizeof(*groups), GFP_KERNEL); > + if (!groups) > + return -ENOMEM; > + > + /* Initialize attribute lists */ > + for (i = 0; i < num_groups; i++) > + INIT_LIST_HEAD(&groups[i].attr_list); > + > + /* Register Counter device attributes */ > + err = counter_device_register(counter, groups);
This function name is a bit misleading. At first I though we were registering a new counter device (struct device). Maybe counter_sysfs_create_attrs() would be a better name? (I wouldn't mind having all functions in this file having a "counter_sysfs_" prefix for that matter.)
> diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c > index 1ff07faef27f..938085dead80 100644 > --- a/drivers/counter/ti-eqep.c > +++ b/drivers/counter/ti-eqep.c
> @@ -406,7 +414,7 @@ static int ti_eqep_probe(struct platform_device *pdev) > > priv->counter.name = dev_name(dev); > priv->counter.parent = dev; > - priv->counter.ops = &ti_eqep_counter_ops; > + priv->counter.parent = &ti_eqep_counter_ops; > priv->counter.counts = ti_eqep_counts; > priv->counter.num_counts = ARRAY_SIZE(ti_eqep_counts); > priv->counter.signals = ti_eqep_signals;
This looks like an unintentional change and causes a compile error.
> diff --git a/include/linux/counter.h b/include/linux/counter.h > index 9dbd5df4cd34..132bfecca5c3 100644 > --- a/include/linux/counter.h > +++ b/include/linux/counter.h > @@ -6,417 +6,195 @@ > #ifndef _COUNTER_H_ > #define _COUNTER_H_ > > -#include <linux/counter_enum.h> > #include <linux/device.h> > +#include <linux/kernel.h> > +#include <linux/list.h>
struct list_head is defined in linux/types.h. Is there something else we are using from linux/list.h in this file?
> #include <linux/types.h> >
It would be helpful to have kernel doc comments on everything in this file.
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