Re: [PATCH v1 1/2] PM: core: Annotate loops walking device links as _srcu

Ulf Hansson
2025-09-04T09:23:56Z

On Tue, 2 Sept 2025 at 15:45, Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Since SRCU is used for the protection of device link lists, the loops
> over device link lists in multiple places in drivers/base/power/main.c
> and in pm_runtime_get_suppliers() should be annotated as _srcu rather
> than as _rcu which is the case currently.
>
> Change the annotations accordingly.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
> drivers/base/power/main.c | 18 +++++++++---------
> drivers/base/power/runtime.c | 4 ++--
> 2 files changed, 11 insertions(+), 11 deletions(-)
>
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -40,8 +40,8 @@
>
> typedef int (*pm_callback_t)(struct device *);
>
> -#define list_for_each_entry_rcu_locked(pos, head, member) \
> - list_for_each_entry_rcu(pos, head, member, \
> +#define list_for_each_entry_srcu_locked(pos, head, member) \
> + list_for_each_entry_srcu(pos, head, member, \
> device_links_read_lock_held())
>
> /*
> @@ -281,7 +281,7 @@
> * callbacks freeing the link objects for the links in the list we're
> * walking.
> */
> - list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node)
> + list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
> if (READ_ONCE(link->status) != DL_STATE_DORMANT)
> dpm_wait(link->supplier, async);
>
> @@ -338,7 +338,7 @@
> * continue instead of trying to continue in parallel with its
> * unregistration).
> */
> - list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node)
> + list_for_each_entry_srcu_locked(link, &dev->links.consumers, s_node)
> if (READ_ONCE(link->status) != DL_STATE_DORMANT)
> dpm_wait(link->consumer, async);
>
> @@ -675,7 +675,7 @@
> idx = device_links_read_lock();
>
> /* Start processing the device's "async" consumers. */
> - list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node)
> + list_for_each_entry_srcu_locked(link, &dev->links.consumers, s_node)
> if (READ_ONCE(link->status) != DL_STATE_DORMANT)
> dpm_async_with_cleanup(link->consumer, func);
>
> @@ -1330,7 +1330,7 @@
> idx = device_links_read_lock();
>
> /* Start processing the device's "async" suppliers. */
> - list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node)
> + list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
> if (READ_ONCE(link->status) != DL_STATE_DORMANT)
> dpm_async_with_cleanup(link->supplier, func);
>
> @@ -1384,7 +1384,7 @@
>
> idx = device_links_read_lock();
>
> - list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node)
> + list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node)
> link->supplier->power.must_resume = true;
>
> device_links_read_unlock(idx);
> @@ -1813,7 +1813,7 @@
>
> idx = device_links_read_lock();
>
> - list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node) {
> + list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node) {
> spin_lock_irq(&link->supplier->power.lock);
> link->supplier->power.direct_complete = false;
> spin_unlock_irq(&link->supplier->power.lock);
> @@ -2065,7 +2065,7 @@
>
> idx = device_links_read_lock();
>
> - list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node) {
> + list_for_each_entry_srcu_locked(link, &dev->links.suppliers, c_node) {
> if (!device_link_test(link, DL_FLAG_PM_RUNTIME))
> continue;
>
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -1903,8 +1903,8 @@
>
> idx = device_links_read_lock();
>
> - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> - device_links_read_lock_held())
> + list_for_each_entry_srcu(link, &dev->links.suppliers, c_node,
> + device_links_read_lock_held())
> if (device_link_test(link, DL_FLAG_PM_RUNTIME)) {
> link->supplier_preactivated = true;
> pm_runtime_get_sync(link->supplier);
>
>
>