On 15/01/2024 17:06, Bartosz Golaszewski wrote:
>> +
>> +static int __reset_add_reset_gpio_lookup(int id, struct device_node *np,
>> + unsigned int gpio,
>> + unsigned int of_flags)
>> +{
>> + struct gpiod_lookup_table *lookup __free(kfree) = NULL;
>> + struct gpio_device *gdev __free(gpio_device_put) = NULL;
>> + char *label __free(kfree) = NULL;
>
> I got yelled at by Linus Torvalds personally for doing it like this. I
> know this is a common pattern in code using GLib but Linus wants auto
> variables to be initialized where they're declared...
Declaration is here. Initialization is here. Therefore this is
initialized where it is declared. What's more it is initialized to a
valid value, because __free() accepts NULLs.
>
>> + unsigned int lookup_flags;
>> +
>> + /*
>> + * Later we map GPIO flags between OF and Linux, however not all
>> + * constants from include/dt-bindings/gpio/gpio.h and
>> + * include/linux/gpio/machine.h match each other.
>> + */
>> + if (of_flags > GPIO_ACTIVE_LOW) {
>> + pr_err("reset-gpio code does not support GPIO flags %u for GPIO %u\n",
>> + of_flags, gpio);
>> + return -EINVAL;
>> + }
>> +
>> + gdev = gpio_device_find_by_fwnode(of_fwnode_handle(np));
>
> ... so this should become:
>
> struct gpio_device *gdev __free(gpio_device_put) = gpio_device_find(...)
>
> and same for the rest.
>
> Don't get me wrong, I love cleanup.h but there's a (unofficial for
> now) coding style.
So you just want to declare it not in top-part of the function but just
before first use?
>
>> + if (!gdev)
>> + return -EPROBE_DEFER;
>> +
>> + label = kstrdup(gpio_device_get_label(gdev), GFP_KERNEL);
>> + if (!label)
>> + return -EINVAL;
>> +
>> + /* Size: one lookup entry plus sentinel */
>> + lookup = kzalloc(struct_size(lookup, table, 2), GFP_KERNEL);
>> + if (!lookup)
>> + return -ENOMEM;
>> +
>> + lookup->dev_id = kasprintf(GFP_KERNEL, "reset-gpio.%d", id);
>> + if (!lookup->dev_id)
>> + return -ENOMEM;
>> +
>> + lookup_flags = GPIO_PERSISTENT;
>> + lookup_flags |= of_flags & GPIO_ACTIVE_LOW;
>> + lookup->table[0] = GPIO_LOOKUP(no_free_ptr(label), gpio, "reset",
>> + lookup_flags);
>> +
>> + gpiod_add_lookup_table(no_free_ptr(lookup));
>
> You told me that this doesn't need to be removed or ever freed but a
> comment on that would be in order.
Sure, code further comments on this but I can make it explicit here as well.
>
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * @reset_args: phandle to the GPIO provider with all the args like GPIO number
>> + */
>> +static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
>> +{
>> + struct reset_gpio_lookup *rgpio_dev;
>> + struct platform_device *pdev;
>> + int id, ret;
>> +
>> + /*
>> + * Registering reset-gpio device might cause immediate
>> + * bind, resulting in its probe() registering new reset controller thus
>> + * taking reset_list_mutex lock via reset_controller_register().
>> + */
>> + lockdep_assert_not_held(&reset_list_mutex);
>
> So how does dumping the stack help here exactly?
This is self-documenting code. dumping stack does not matter, the point
is that future developers should see this lockdep before they start
playing with new locks.
>
>> +
>> + mutex_lock(&reset_gpio_lookup_mutex);
>> +
>> + list_for_each_entry(rgpio_dev, &reset_gpio_lookup_list, list) {
>> + if (args->np == rgpio_dev->of_args.np) {
>> + if (__reset_gpios_args_match(args, &rgpio_dev->of_args))
>> + goto out; /* Already on the list, done */
>> + }
>> + }
>> +
>> + id = ida_alloc(&reset_gpio_ida, GFP_KERNEL);
>> + if (id < 0) {
>> + ret = id;
>> + goto err_unlock;
>> + }
>> +
>> + /*
>> + * Not freed in normal path, persisent subsystem data (which is assumed
>> + * also in the reset-gpio driver).
>> + */
>> + rgpio_dev = kzalloc(sizeof(*rgpio_dev), GFP_KERNEL);
>> + if (!rgpio_dev) {
>> + ret = -ENOMEM;
>> + goto err_ida_free;
>> + }
>> +
>> + ret = __reset_add_reset_gpio_lookup(id, args->np, args->args[0],
>> + args->args[1]);
>> + if (ret < 0)
>> + goto err_kfree;
>> +
>> + rgpio_dev->of_args = *args;
>> + /*
>> + * We keep the device_node reference, but of_args.np is put at the end
>> + * of __of_reset_control_get(), so get it one more time.
>> + * Hold reference as long as rgpio_dev memory is valid.
>> + */
>> + of_node_get(rgpio_dev->of_args.np);
>> + pdev = platform_device_register_data(NULL, "reset-gpio", id,
>> + &rgpio_dev->of_args,
>> + sizeof(rgpio_dev->of_args));
>> + ret = PTR_ERR_OR_ZERO(pdev);
>> + if (ret)
>> + goto err_put;
>> +
>> + list_add(&rgpio_dev->list, &reset_gpio_lookup_list);
>> +
>> +out:
>> + mutex_unlock(&reset_gpio_lookup_mutex);
>> +
>> + return 0;
>> +
>> +err_put:
>> + of_node_put(rgpio_dev->of_args.np);
>> +err_kfree:
>> + kfree(rgpio_dev);
>> +err_ida_free:
>> + ida_free(&reset_gpio_ida, id);
>> +err_unlock:
>> + mutex_unlock(&reset_gpio_lookup_mutex);
>> +
>
> You're already using cleanup helpers above, why not here too? Would
> make this function much more readable and allow you to drop all but
Not sure how much it would be cleaner considering that these are not
free on success.
> the ida_free() here. Possibly you'd need to define the __free()
> callback for of_node_put() though.
>
>> + return ret;
>> +}
>> +
>> +static struct reset_controller_dev *__reset_find_rcdev(const struct of_phandle_args *args,
>> + bool gpio_fallback)
>> +{
>> + struct reset_controller_dev *r, *rcdev;
>> +
>> + lockdep_assert_held(&reset_list_mutex);
>> +
>> + rcdev = NULL;
>> + list_for_each_entry(r, &reset_controller_list, list) {
>> + if (args->np == r->of_node) {
>> + if (gpio_fallback) {
>> + if (__reset_gpios_args_match(args, r->of_args)) {
>> + rcdev = r;
>> + break;
>> + }
>> + } else {
>> + rcdev = r;
>> + break;
>> + }
>> + }
>> + }
>> +
>> + return rcdev;
>> +}
>> +
>> struct reset_control *
>> __of_reset_control_get(struct device_node *node, const char *id, int index,
>> bool shared, bool optional, bool acquired)
>> {
>> + struct of_phandle_args args = {0};
>> + bool gpio_fallback = false;
>> struct reset_control *rstc;
>> - struct reset_controller_dev *r, *rcdev;
>> - struct of_phandle_args args;
>> + struct reset_controller_dev *rcdev;
>> int rstc_id;
>> int ret;
>>
>> @@ -839,39 +1028,49 @@ __of_reset_control_get(struct device_node *node, const char *id, int index,
>> index, &args);
>> if (ret == -EINVAL)
>> return ERR_PTR(ret);
>> - if (ret)
>> - return optional ? NULL : ERR_PTR(ret);
>> + if (ret) {
>> + /*
>> + * There can be only one reset-gpio for regular devices, so
>> + * don't bother with GPIO index.
>> + */
>> + ret = of_parse_phandle_with_args(node, "reset-gpios", "#gpio-cells",
>> + 0, &args);
>> + if (ret)
>> + return optional ? NULL : ERR_PTR(ret);
>>
>> - mutex_lock(&reset_list_mutex);
>> - rcdev = NULL;
>> - list_for_each_entry(r, &reset_controller_list, list) {
>> - if (args.np == r->of_node) {
>> - rcdev = r;
>> - break;
>> + gpio_fallback = true;
>> +
>> + ret = __reset_add_reset_gpio_device(&args);
>> + if (ret) {
>> + rstc = ERR_PTR(ret);
>> + goto out_put;
>> }
>> }
>>
>> + mutex_lock(&reset_list_mutex);
>> + rcdev = __reset_find_rcdev(&args, gpio_fallback);
>> if (!rcdev) {
>> rstc = ERR_PTR(-EPROBE_DEFER);
>> - goto out;
>> + goto out_unlock;
>> }
>>
>> if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
>> rstc = ERR_PTR(-EINVAL);
>> - goto out;
>> + goto out_unlock;
>> }
>>
>> rstc_id = rcdev->of_xlate(rcdev, &args);
>> if (rstc_id < 0) {
>> rstc = ERR_PTR(rstc_id);
>> - goto out;
>> + goto out_unlock;
>> }
>>
>> /* reset_list_mutex also protects the rcdev's reset_control list */
>> rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
>>
>> -out:
>> +out_unlock:
>> mutex_unlock(&reset_list_mutex);
>> +out_put:
>> of_node_put(args.np);
>
> I suggest reworking this to use cleanup.h as well.
It's independent task. This is an existing code and any refactoring to
cleanup or not is independent thing.
Best regards,
Krzysztof
