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

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Message-ID: <CAPDyKFp5NbEtiLRZihta0y=DXSTKghnfGHH1N_Y1BF=Q73eTtA@mail.gmail.com>
Date: Thu, 4 Sep 2025 11:23:18 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Linux PM <linux-pm@...r.kernel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, LKML <linux-kernel@...r.kernel.org>, 
	Danilo Krummrich <dakr@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
	Johannes Berg <johannes@...solutions.net>
Subject: Re: [PATCH v1 1/2] PM: core: Annotate loops walking device links as _srcu

On Tue, 2 Sept 2025 at 15:45, Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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@...el.com>

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.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);
>
>
>