gpiolib: use a single SRCU struct for all GPIO descriptors
We used a per-descriptor SRCU struct in order to not impose a wait with synchronize_srcu() for descriptor X on read-only operations of descriptor Y. Now that we no longer call synchronize_srcu() on descriptor label change but only when releasing descriptor resources, we can use a single SRCU structure for all GPIO descriptors in a given chip. Suggested-by: "Paul E. McKenney" <paulmck@kernel.org> Acked-by: "Paul E. McKenney" <paulmck@kernel.org> Link: https://lore.kernel.org/r/20240507172414.28513-1-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski
parent
a86d276930
commit
7765ffed53
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@ -2351,7 +2351,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
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dflags = READ_ONCE(desc->flags);
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scoped_guard(srcu, &desc->srcu) {
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scoped_guard(srcu, &desc->gdev->desc_srcu) {
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label = gpiod_get_label(desc);
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if (label && test_bit(FLAG_REQUESTED, &dflags))
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strscpy(info->consumer, label,
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@ -112,8 +112,8 @@ const char *gpiod_get_label(struct gpio_desc *desc)
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if (!test_bit(FLAG_REQUESTED, &flags))
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return NULL;
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label = srcu_dereference_check(desc->label, &desc->srcu,
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srcu_read_lock_held(&desc->srcu));
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label = srcu_dereference_check(desc->label, &desc->gdev->desc_srcu,
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srcu_read_lock_held(&desc->gdev->desc_srcu));
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return label->str;
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}
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@ -138,7 +138,7 @@ static int desc_set_label(struct gpio_desc *desc, const char *label)
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old = rcu_replace_pointer(desc->label, new, 1);
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if (old)
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call_srcu(&desc->srcu, &old->rh, desc_free_label);
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call_srcu(&desc->gdev->desc_srcu, &old->rh, desc_free_label);
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return 0;
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}
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@ -709,13 +709,10 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
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static void gpiodev_release(struct device *dev)
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{
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struct gpio_device *gdev = to_gpio_device(dev);
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unsigned int i;
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for (i = 0; i < gdev->ngpio; i++) {
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/* Free pending label. */
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synchronize_srcu(&gdev->descs[i].srcu);
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cleanup_srcu_struct(&gdev->descs[i].srcu);
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}
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/* Call pending kfree()s for descriptor labels. */
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synchronize_srcu(&gdev->desc_srcu);
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cleanup_srcu_struct(&gdev->desc_srcu);
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ida_free(&gpio_ida, gdev->id);
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kfree_const(gdev->label);
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@ -992,6 +989,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
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if (ret)
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goto err_remove_from_list;
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ret = init_srcu_struct(&gdev->desc_srcu);
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if (ret)
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goto err_cleanup_gdev_srcu;
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#ifdef CONFIG_PINCTRL
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INIT_LIST_HEAD(&gdev->pin_ranges);
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#endif
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@ -999,23 +1000,19 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
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if (gc->names) {
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ret = gpiochip_set_desc_names(gc);
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if (ret)
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goto err_cleanup_gdev_srcu;
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goto err_cleanup_desc_srcu;
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}
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ret = gpiochip_set_names(gc);
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if (ret)
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goto err_cleanup_gdev_srcu;
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goto err_cleanup_desc_srcu;
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ret = gpiochip_init_valid_mask(gc);
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if (ret)
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goto err_cleanup_gdev_srcu;
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goto err_cleanup_desc_srcu;
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for (desc_index = 0; desc_index < gc->ngpio; desc_index++) {
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struct gpio_desc *desc = &gdev->descs[desc_index];
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ret = init_srcu_struct(&desc->srcu);
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if (ret)
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goto err_cleanup_desc_srcu;
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if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
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assign_bit(FLAG_IS_OUT,
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&desc->flags, !gc->get_direction(gc, desc_index));
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@ -1027,7 +1024,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
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ret = of_gpiochip_add(gc);
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if (ret)
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goto err_cleanup_desc_srcu;
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goto err_free_valid_mask;
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ret = gpiochip_add_pin_ranges(gc);
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if (ret)
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@ -1074,10 +1071,10 @@ err_free_hogs:
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gpiochip_remove_pin_ranges(gc);
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err_remove_of_chip:
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of_gpiochip_remove(gc);
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err_cleanup_desc_srcu:
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while (desc_index--)
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cleanup_srcu_struct(&gdev->descs[desc_index].srcu);
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err_free_valid_mask:
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gpiochip_free_valid_mask(gc);
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err_cleanup_desc_srcu:
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cleanup_srcu_struct(&gdev->desc_srcu);
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err_cleanup_gdev_srcu:
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cleanup_srcu_struct(&gdev->srcu);
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err_remove_from_list:
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@ -2407,7 +2404,7 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
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if (!test_bit(FLAG_REQUESTED, &desc->flags))
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return NULL;
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guard(srcu)(&desc->srcu);
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guard(srcu)(&desc->gdev->desc_srcu);
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label = kstrdup(gpiod_get_label(desc), GFP_KERNEL);
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if (!label)
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@ -4798,7 +4795,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
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}
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for_each_gpio_desc(gc, desc) {
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guard(srcu)(&desc->srcu);
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guard(srcu)(&desc->gdev->desc_srcu);
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if (test_bit(FLAG_REQUESTED, &desc->flags)) {
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gpiod_get_direction(desc);
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is_out = test_bit(FLAG_IS_OUT, &desc->flags);
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@ -31,6 +31,7 @@
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* @chip: pointer to the corresponding gpiochip, holding static
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* data for this device
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* @descs: array of ngpio descriptors.
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* @desc_srcu: ensures consistent state of GPIO descriptors exposed to users
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* @ngpio: the number of GPIO lines on this GPIO device, equal to the size
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* of the @descs array.
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* @can_sleep: indicate whether the GPIO chip driver's callbacks can sleep
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@ -61,6 +62,7 @@ struct gpio_device {
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struct module *owner;
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struct gpio_chip __rcu *chip;
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struct gpio_desc *descs;
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struct srcu_struct desc_srcu;
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int base;
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u16 ngpio;
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bool can_sleep;
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@ -150,7 +152,6 @@ struct gpio_desc_label {
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* @label: Name of the consumer
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* @name: Line name
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* @hog: Pointer to the device node that hogs this line (if any)
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* @srcu: SRCU struct protecting the label pointer.
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*
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* These are obtained using gpiod_get() and are preferable to the old
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* integer-based handles.
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@ -188,7 +189,6 @@ struct gpio_desc {
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#ifdef CONFIG_OF_DYNAMIC
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struct device_node *hog;
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#endif
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struct srcu_struct srcu;
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};
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#define gpiod_not_found(desc) (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
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@ -256,7 +256,7 @@ static inline int gpio_chip_hwgpio(const struct gpio_desc *desc)
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#define gpiod_err(desc, fmt, ...) \
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do { \
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scoped_guard(srcu, &desc->srcu) { \
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scoped_guard(srcu, &desc->gdev->desc_srcu) { \
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pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), \
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gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \
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} \
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@ -264,7 +264,7 @@ do { \
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#define gpiod_warn(desc, fmt, ...) \
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do { \
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scoped_guard(srcu, &desc->srcu) { \
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scoped_guard(srcu, &desc->gdev->desc_srcu) { \
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pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), \
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gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \
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} \
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@ -272,7 +272,7 @@ do { \
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#define gpiod_dbg(desc, fmt, ...) \
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do { \
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scoped_guard(srcu, &desc->srcu) { \
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scoped_guard(srcu, &desc->gdev->desc_srcu) { \
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pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), \
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gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \
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} \
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