linux-kernel - [PATCH v3 7/9] PM: sleep: Add strict_midlayer flag to struct dev_pm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <24017035.6Emhk5qWAg@rjwysocki.net>
Date: Fri, 27 Jun 2025 21:23:42 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Linux ACPI <linux-acpi@...r.kernel.org>,
 Linux PCI <linux-pci@...r.kernel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject:
 [PATCH v3 7/9] PM: sleep: Add strict_midlayer flag to struct dev_pm_info

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Add a new flag, called strict_midlayer, to struct dev_pm_info, along
with helper functions for updating and reading its value, to allow
middle layer code that provides proper callbacks for device suspend-
resume during system-wide PM transitions to let pm_runtime_force_suspend()
and and pm_runtime_force_resume() know that they should only invoke
runtime PM callbacks coming from the device's driver.

Namely, if this flag is set, pm_runtime_force_suspend() and
and pm_runtime_force_resume() will invoke runtime PM callbacks
provided by the device's driver directly with the assumption that
they have been called via a middle layer callback for device suspend
or resume, respectively.

For instance, acpi_general_pm_domain provides specific
callback functions for system suspend, acpi_subsys_suspend(),
acpi_subsys_suspend_late() and acpi_subsys_suspend_noirq(), and
it does not expect its runtime suspend callback function,
acpi_subsys_runtime_suspend(), to be invoked at any point during
system suspend. In particular, it does not expect that function
to be called from within any of the system suspend callback functions
mentioned above which would happen if a device driver collaborating
with acpi_general_pm_domain used pm_runtime_force_suspend() as its
callback function for any system suspend phase later than "prepare".

The new flag allows this expectation of acpi_general_pm_domain to
be formally expressed, which is going to be done subsequently.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

v2 -> v3:
   * Add a kerneldoc comment for dev_pm_set_strict_midlayer() (Bjorn).
   * Update changelog (minor tweaks).

v1 -> v2:
   * Rename dev_pm_strict_midlayer() to dev_pm_set_strict_midlayer().
   * Add dev_pm_strict_midlayer_is_set() and use it in get_callback()
     because pm_runtime_force_suspend() can be used in driver remove
     callbacks and so it needs to work with CONFIG_PM_SLEEP unset.

---
 drivers/base/power/runtime.c |   21 +++++++++++++++++++--
 include/linux/device.h       |   27 +++++++++++++++++++++++++++
 include/linux/pm.h           |    1 +
 3 files changed, 47 insertions(+), 2 deletions(-)

--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1958,6 +1958,23 @@
 	pm_request_idle(link->supplier);
 }
 
+static pm_callback_t get_callback(struct device *dev, size_t cb_offset)
+{
+	/*
+	 * Setting power.strict_midlayer means that the middle layer
+	 * code does not want its runtime PM callbacks to be invoked via
+	 * pm_runtime_force_suspend() and pm_runtime_force_resume(), so
+	 * return a direct pointer to the driver callback in that case.
+	 */
+	if (dev_pm_strict_midlayer_is_set(dev))
+		return __rpm_get_driver_callback(dev, cb_offset);
+
+	return __rpm_get_callback(dev, cb_offset);
+}
+
+#define GET_CALLBACK(dev, callback) \
+		get_callback(dev, offsetof(struct dev_pm_ops, callback))
+
 /**
  * pm_runtime_force_suspend - Force a device into suspend state if needed.
  * @dev: Device to suspend.
@@ -1984,7 +2001,7 @@
 	if (pm_runtime_status_suspended(dev) || dev->power.needs_force_resume)
 		return 0;
 
-	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
+	callback = GET_CALLBACK(dev, runtime_suspend);
 
 	dev_pm_enable_wake_irq_check(dev, true);
 	ret = callback ? callback(dev) : 0;
@@ -2046,7 +2063,7 @@
 	    pm_runtime_status_suspended(dev)))
 		goto out;
 
-	callback = RPM_GET_CALLBACK(dev, runtime_resume);
+	callback = GET_CALLBACK(dev, runtime_resume);
 
 	dev_pm_disable_wake_irq_check(dev, false);
 	ret = callback ? callback(dev) : 0;
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -879,6 +879,33 @@
 #endif
 }
 
+/*
+ * dev_pm_set_strict_midlayer - Update the device's power.strict_midlayer flag
+ * @dev: Target device.
+ * @val: New flag value.
+ *
+ * When set, power.strict_midlayer means that the middle layer power management
+ * code (typically, a bus type or a PM domain) does not expect its runtime PM
+ * suspend callback to be invoked at all during system-wide PM transitions and
+ * it does not expect its runtime PM resume callback to be invoked at any point
+ * when runtime PM is disabled for the device during system-wide PM transitions.
+ */
+static inline void dev_pm_set_strict_midlayer(struct device *dev, bool val)
+{
+#ifdef CONFIG_PM_SLEEP
+	dev->power.strict_midlayer = val;
+#endif
+}
+
+static inline bool dev_pm_strict_midlayer_is_set(struct device *dev)
+{
+#ifdef CONFIG_PM_SLEEP
+	return dev->power.strict_midlayer;
+#else
+	return false;
+#endif
+}
+
 static inline void device_lock(struct device *dev)
 {
 	mutex_lock(&dev->mutex);
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -683,6 +683,7 @@
 	bool			smart_suspend:1;	/* Owned by the PM core */
 	bool			must_resume:1;		/* Owned by the PM core */
 	bool			may_skip_resume:1;	/* Set by subsystems */
+	bool			strict_midlayer:1;
 #else
 	bool			should_wakeup:1;
 #endif