[PATCH 2/3] PM/shutdown: device_shutdown() uses the order info in dpm_list instead of devices_kset

From: Pingfan Liu
Date: Mon Aug 20 2018 - 05:19:05 EST

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At present, the "parent <- child" and "suppiler <- consumer" ordering info
are stored duplicate in two places dpm_list and devices_kset, and
corresponding, there are two sets of routines to manipulate them. The patch
pushes the dpm_list and dpm_list_mtx out of CONFIG_PM, and let
device_shutdown() use them to implement shutdown seq. Comparing to original
code, this patch tries to simplify the code at the cost of a extra mutex if
without CONFIG_PM and nothing if with CONFIG_PM. The cost on dpm_list_mtx
can be ignored, since the device hot add/remove is not very frequently.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
---
drivers/base/power/main.c | 119 ++++++++++++------------------------------
drivers/base/power/power.h | 25 +++++----
drivers/base/power/shutdown.c | 63 +++++++++++++++++++---
include/linux/pm.h | 7 +--
4 files changed, 104 insertions(+), 110 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 3f68e29..7b2f316 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -49,14 +49,12 @@ typedef int (*pm_callback_t)(struct device *);
* dpm_list_mutex.
*/

-LIST_HEAD(dpm_list);
static LIST_HEAD(dpm_prepared_list);
static LIST_HEAD(dpm_suspended_list);
static LIST_HEAD(dpm_late_early_list);
static LIST_HEAD(dpm_noirq_list);

struct suspend_stats suspend_stats;
-static DEFINE_MUTEX(dpm_list_mtx);
static pm_message_t pm_transition;

static int async_error;
@@ -98,59 +96,6 @@ void device_pm_sleep_init(struct device *dev)
init_completion(&dev->power.completion);
complete_all(&dev->power.completion);
dev->power.wakeup = NULL;
- INIT_LIST_HEAD(&dev->power.entry);
-}
-
-/**
- * device_pm_lock - Lock the list of active devices used by the PM core.
- */
-void device_pm_lock(void)
-{
- mutex_lock(&dpm_list_mtx);
-}
-
-/**
- * device_pm_unlock - Unlock the list of active devices used by the PM core.
- */
-void device_pm_unlock(void)
-{
- mutex_unlock(&dpm_list_mtx);
-}
-
-/**
- * device_pm_add - Add a device to the PM core's list of active devices.
- * @dev: Device to add to the list.
- */
-void device_pm_add(struct device *dev)
-{
- pr_debug("PM: Adding info for %s:%s\n",
- dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
- device_pm_check_callbacks(dev);
- mutex_lock(&dpm_list_mtx);
- if (dev->parent && dev->parent->power.is_prepared)
- dev_warn(dev, "parent %s should not be sleeping\n",
- dev_name(dev->parent));
- list_add_tail(&dev->power.entry, &dpm_list);
- dev->power.in_dpm_list = true;
- mutex_unlock(&dpm_list_mtx);
-}
-
-/**
- * device_pm_remove - Remove a device from the PM core's list of active devices.
- * @dev: Device to be removed from the list.
- */
-void device_pm_remove(struct device *dev)
-{
- pr_debug("PM: Removing info for %s:%s\n",
- dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
- complete_all(&dev->power.completion);
- mutex_lock(&dpm_list_mtx);
- list_del_init(&dev->power.entry);
- dev->power.in_dpm_list = false;
- mutex_unlock(&dpm_list_mtx);
- device_wakeup_disable(dev);
- pm_runtime_remove(dev);
- device_pm_check_callbacks(dev);
}

/**
@@ -714,7 +659,7 @@ void dpm_noirq_resume_devices(pm_message_t state)
ktime_t starttime = ktime_get();

trace_suspend_resume(TPS("dpm_resume_noirq"), state.event, true);
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;

/*
@@ -734,7 +679,7 @@ void dpm_noirq_resume_devices(pm_message_t state)
dev = to_device(dpm_noirq_list.next);
get_device(dev);
list_move_tail(&dev->power.entry, &dpm_late_early_list);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

if (!is_async(dev)) {
int error;
@@ -748,10 +693,10 @@ void dpm_noirq_resume_devices(pm_message_t state)
}
}

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
put_device(dev);
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
dpm_show_time(starttime, state, 0, "noirq");
trace_suspend_resume(TPS("dpm_resume_noirq"), state.event, false);
@@ -871,7 +816,7 @@ void dpm_resume_early(pm_message_t state)
ktime_t starttime = ktime_get();

trace_suspend_resume(TPS("dpm_resume_early"), state.event, true);
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;

/*
@@ -891,7 +836,7 @@ void dpm_resume_early(pm_message_t state)
dev = to_device(dpm_late_early_list.next);
get_device(dev);
list_move_tail(&dev->power.entry, &dpm_suspended_list);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

if (!is_async(dev)) {
int error;
@@ -904,10 +849,10 @@ void dpm_resume_early(pm_message_t state)
pm_dev_err(dev, state, " early", error);
}
}
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
put_device(dev);
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
dpm_show_time(starttime, state, 0, "early");
trace_suspend_resume(TPS("dpm_resume_early"), state.event, false);
@@ -1039,7 +984,7 @@ void dpm_resume(pm_message_t state)
trace_suspend_resume(TPS("dpm_resume"), state.event, true);
might_sleep();

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;
async_error = 0;

@@ -1057,7 +1002,7 @@ void dpm_resume(pm_message_t state)
if (!is_async(dev)) {
int error;

- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

error = device_resume(dev, state, false);
if (error) {
@@ -1067,13 +1012,13 @@ void dpm_resume(pm_message_t state)
pm_dev_err(dev, state, "", error);
}

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
}
if (!list_empty(&dev->power.entry))
list_move_tail(&dev->power.entry, &dpm_prepared_list);
put_device(dev);
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
dpm_show_time(starttime, state, 0, NULL);

@@ -1140,24 +1085,24 @@ void dpm_complete(pm_message_t state)
might_sleep();

INIT_LIST_HEAD(&list);
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
while (!list_empty(&dpm_prepared_list)) {
struct device *dev = to_device(dpm_prepared_list.prev);

get_device(dev);
dev->power.is_prepared = false;
list_move(&dev->power.entry, &list);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

trace_device_pm_callback_start(dev, "", state.event);
device_complete(dev, state);
trace_device_pm_callback_end(dev, 0);

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
put_device(dev);
}
list_splice(&list, &dpm_list);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

/* Allow device probing and trigger re-probing of deferred devices */
device_unblock_probing();
@@ -1385,7 +1330,7 @@ int dpm_noirq_suspend_devices(pm_message_t state)
int error = 0;

trace_suspend_resume(TPS("dpm_suspend_noirq"), state.event, true);
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;
async_error = 0;

@@ -1393,11 +1338,11 @@ int dpm_noirq_suspend_devices(pm_message_t state)
struct device *dev = to_device(dpm_late_early_list.prev);

get_device(dev);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

error = device_suspend_noirq(dev);

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
if (error) {
pm_dev_err(dev, state, " noirq", error);
dpm_save_failed_dev(dev_name(dev));
@@ -1411,7 +1356,7 @@ int dpm_noirq_suspend_devices(pm_message_t state)
if (async_error)
break;
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
if (!error)
error = async_error;
@@ -1586,7 +1531,7 @@ int dpm_suspend_late(pm_message_t state)
int error = 0;

trace_suspend_resume(TPS("dpm_suspend_late"), state.event, true);
- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;
async_error = 0;

@@ -1594,11 +1539,11 @@ int dpm_suspend_late(pm_message_t state)
struct device *dev = to_device(dpm_suspended_list.prev);

get_device(dev);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

error = device_suspend_late(dev);

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
if (!list_empty(&dev->power.entry))
list_move(&dev->power.entry, &dpm_late_early_list);

@@ -1613,7 +1558,7 @@ int dpm_suspend_late(pm_message_t state)
if (async_error)
break;
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
if (!error)
error = async_error;
@@ -1851,18 +1796,18 @@ int dpm_suspend(pm_message_t state)

cpufreq_suspend();

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
pm_transition = state;
async_error = 0;
while (!list_empty(&dpm_prepared_list)) {
struct device *dev = to_device(dpm_prepared_list.prev);

get_device(dev);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

error = device_suspend(dev);

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
if (error) {
pm_dev_err(dev, state, "", error);
dpm_save_failed_dev(dev_name(dev));
@@ -1875,7 +1820,7 @@ int dpm_suspend(pm_message_t state)
if (async_error)
break;
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
async_synchronize_full();
if (!error)
error = async_error;
@@ -1989,18 +1934,18 @@ int dpm_prepare(pm_message_t state)
*/
device_block_probing();

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
while (!list_empty(&dpm_list)) {
struct device *dev = to_device(dpm_list.next);

get_device(dev);
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();

trace_device_pm_callback_start(dev, "", state.event);
error = device_prepare(dev, state);
trace_device_pm_callback_end(dev, error);

- mutex_lock(&dpm_list_mtx);
+ device_pm_lock();
if (error) {
if (error == -EAGAIN) {
put_device(dev);
@@ -2018,7 +1963,7 @@ int dpm_prepare(pm_message_t state)
list_move_tail(&dev->power.entry, &dpm_prepared_list);
put_device(dev);
}
- mutex_unlock(&dpm_list_mtx);
+ device_pm_unlock();
trace_suspend_resume(TPS("dpm_prepare"), state.event, false);
return error;
}
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index c511def..4578d97 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -1,15 +1,31 @@
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/pm_qos.h>

+extern struct mutex dpm_list_mtx;
+
+static inline void device_pm_lock(void)
+{
+ mutex_lock(&dpm_list_mtx);
+}
+
+static inline void device_pm_unlock(void)
+{
+ mutex_unlock(&dpm_list_mtx);
+}
+
static inline void device_pm_init_common(struct device *dev)
{
if (!dev->power.early_init) {
spin_lock_init(&dev->power.lock);
+ INIT_LIST_HEAD(&dev->power.entry);
dev->power.qos = NULL;
dev->power.early_init = true;
}
}

+extern void device_pm_add(struct device *dev);
+extern void device_pm_remove(struct device *dev);
+
#ifdef CONFIG_PM

static inline void pm_runtime_early_init(struct device *dev)
@@ -104,8 +120,6 @@ static inline struct device *to_device(struct list_head *entry)
}

extern void device_pm_sleep_init(struct device *dev);
-extern void device_pm_add(struct device *);
-extern void device_pm_remove(struct device *);
extern void device_pm_move_before(struct device *, struct device *);
extern void device_pm_move_after(struct device *, struct device *);
extern void device_pm_move_last(struct device *);
@@ -120,13 +134,6 @@ static inline bool device_pm_initialized(struct device *dev)

static inline void device_pm_sleep_init(struct device *dev) {}

-static inline void device_pm_add(struct device *dev) {}
-
-static inline void device_pm_remove(struct device *dev)
-{
- pm_runtime_remove(dev);
-}
-
static inline void device_pm_move_before(struct device *deva,
struct device *devb) {}
static inline void device_pm_move_after(struct device *deva,
diff --git a/drivers/base/power/shutdown.c b/drivers/base/power/shutdown.c
index c405d09..be8e247 100644
--- a/drivers/base/power/shutdown.c
+++ b/drivers/base/power/shutdown.c
@@ -5,6 +5,50 @@

#include "../base.h"
#include "power.h"
+
+LIST_HEAD(dpm_list);
+DEFINE_MUTEX(dpm_list_mtx);
+
+/**
+ * device_pm_add - Add a device to the PM core's list of active devices.
+ * @dev: Device to add to the list.
+ */
+void device_pm_add(struct device *dev)
+{
+ pr_debug("PM: Adding info for %s:%s\n",
+ dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
+ device_pm_check_callbacks(dev);
+ device_pm_lock();
+#ifdef CONFIG_PM_SLEEP
+ if (dev->parent && dev->parent->power.is_prepared)
+ dev_warn(dev, "parent %s should not be sleeping\n",
+ dev_name(dev->parent));
+#endif
+ list_add_tail(&dev->power.entry, &dpm_list);
+ dev->power.in_dpm_list = true;
+ device_pm_unlock();
+}
+
+/**
+ * device_pm_remove - Remove a device from the PM core's list of active devices.
+ * @dev: Device to be removed from the list.
+ */
+void device_pm_remove(struct device *dev)
+{
+ pr_debug("PM: Removing info for %s:%s\n",
+ dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
+#ifdef CONFIG_PM_SLEEP
+ complete_all(&dev->power.completion);
+#endif
+ device_pm_lock();
+ list_del_init(&dev->power.entry);
+ dev->power.in_dpm_list = false;
+ device_pm_unlock();
+ device_wakeup_disable(dev);
+ pm_runtime_remove(dev);
+ device_pm_check_callbacks(dev);
+}
+
/**
* device_shutdown - call ->shutdown() on each device to shutdown.
*/
@@ -15,15 +59,18 @@ void device_shutdown(void)
wait_for_device_probe();
device_block_probing();

- spin_lock(&devices_kset->list_lock);
+ /*
+ * only care about race with hotplug. And shutdown excludes suspend
+ */
+ device_pm_lock();
/*
* Walk the devices list backward, shutting down each in turn.
* Beware that device unplug events may also start pulling
* devices offline, even as the system is shutting down.
*/
- while (!list_empty(&devices_kset->list)) {
- dev = list_entry(devices_kset->list.prev, struct device,
- kobj.entry);
+ while (!list_empty(&dpm_list)) {
+ dev = list_entry(dpm_list.prev, struct device,
+ power.entry);

/*
* hold reference count of device's parent to
@@ -36,8 +83,8 @@ void device_shutdown(void)
* Make sure the device is off the kset list, in the
* event that dev->*->shutdown() doesn't remove it.
*/
- list_del_init(&dev->kobj.entry);
- spin_unlock(&devices_kset->list_lock);
+ list_del_init(&dev->power.entry);
+ device_pm_unlock();

/* hold lock to avoid race with probe/release */
if (parent)
@@ -70,7 +117,7 @@ void device_shutdown(void)
put_device(dev);
put_device(parent);

- spin_lock(&devices_kset->list_lock);
+ device_pm_lock();
}
- spin_unlock(&devices_kset->list_lock);
+ device_pm_unlock();
}
diff --git a/include/linux/pm.h b/include/linux/pm.h
index e723b78..77d8a50 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -595,8 +595,8 @@ struct dev_pm_info {
bool direct_complete:1; /* Owned by the PM core */
u32 driver_flags;
spinlock_t lock;
-#ifdef CONFIG_PM_SLEEP
struct list_head entry;
+#ifdef CONFIG_PM_SLEEP
struct completion completion;
struct wakeup_source *wakeup;
bool wakeup_path:1;
@@ -721,7 +721,6 @@ struct dev_pm_domain {
*/

#ifdef CONFIG_PM_SLEEP
-extern void device_pm_lock(void);
extern void dpm_resume_start(pm_message_t state);
extern void dpm_resume_end(pm_message_t state);
extern void dpm_noirq_resume_devices(pm_message_t state);
@@ -731,7 +730,6 @@ extern void dpm_resume_early(pm_message_t state);
extern void dpm_resume(pm_message_t state);
extern void dpm_complete(pm_message_t state);

-extern void device_pm_unlock(void);
extern int dpm_suspend_end(pm_message_t state);
extern int dpm_suspend_start(pm_message_t state);
extern void dpm_noirq_begin(void);
@@ -778,9 +776,6 @@ extern bool dev_pm_smart_suspend_and_suspended(struct device *dev);

#else /* !CONFIG_PM_SLEEP */

-#define device_pm_lock() do {} while (0)
-#define device_pm_unlock() do {} while (0)
-
static inline int dpm_suspend_start(pm_message_t state)
{
return 0;
--
2.7.4

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