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Message-ID: <6198088.lOV4Wx5bFT@rjwysocki.net>
Date: Wed, 16 Jul 2025 21:31:23 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
Saravana Kannan <saravanak@...gle.com>
Subject:
[PATCH v1] PM: sleep: Rearrange suspend/resume error handling in the core
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Notice that device_suspend_noirq(), device_suspend_late() and
device_suspend() all set async_error on errors, so they don't really
need to return a value. Accordingly, make them all void and use
async_error in their callers instead of their return values.
Moreover, since async_error is updated concurrently without locking
during asynchronous suspend and resume processing, use READ_ONCE() and
WRITE_ONCE() for accessing it in those places to ensure that all of the
accesses will be carried out as expected.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
Based on the current linux-pm.git material in linux-next.
---
drivers/base/power/main.c | 79 ++++++++++++++++++++--------------------------
1 file changed, 35 insertions(+), 44 deletions(-)
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -767,7 +767,7 @@
TRACE_RESUME(error);
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async noirq" : " noirq", error);
}
@@ -824,7 +824,7 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
dpm_show_time(starttime, state, 0, "noirq");
- if (async_error)
+ if (READ_ONCE(async_error))
dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
trace_suspend_resume(TPS("dpm_resume_noirq"), state.event, false);
@@ -910,7 +910,7 @@
complete_all(&dev->power.completion);
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async early" : " early", error);
}
@@ -971,7 +971,7 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
dpm_show_time(starttime, state, 0, "early");
- if (async_error)
+ if (READ_ONCE(async_error))
dpm_save_failed_step(SUSPEND_RESUME_EARLY);
trace_suspend_resume(TPS("dpm_resume_early"), state.event, false);
@@ -1086,7 +1086,7 @@
TRACE_RESUME(error);
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async" : "", error);
}
@@ -1150,7 +1150,7 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
dpm_show_time(starttime, state, 0, NULL);
- if (async_error)
+ if (READ_ONCE(async_error))
dpm_save_failed_step(SUSPEND_RESUME);
cpufreq_resume();
@@ -1387,7 +1387,7 @@
* The driver of @dev will not receive interrupts while this function is being
* executed.
*/
-static int device_suspend_noirq(struct device *dev, pm_message_t state, bool async)
+static void device_suspend_noirq(struct device *dev, pm_message_t state, bool async)
{
pm_callback_t callback = NULL;
const char *info = NULL;
@@ -1398,7 +1398,7 @@
dpm_wait_for_subordinate(dev, async);
- if (async_error)
+ if (READ_ONCE(async_error))
goto Complete;
if (dev->power.syscore || dev->power.direct_complete)
@@ -1431,7 +1431,7 @@
Run:
error = dpm_run_callback(callback, dev, state, info);
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async noirq" : " noirq", error);
goto Complete;
@@ -1457,12 +1457,10 @@
complete_all(&dev->power.completion);
TRACE_SUSPEND(error);
- if (error || async_error)
- return error;
+ if (error || READ_ONCE(async_error))
+ return;
dpm_async_suspend_superior(dev, async_suspend_noirq);
-
- return 0;
}
static void async_suspend_noirq(void *data, async_cookie_t cookie)
@@ -1477,7 +1475,7 @@
{
ktime_t starttime = ktime_get();
struct device *dev;
- int error = 0;
+ int error;
trace_suspend_resume(TPS("dpm_suspend_noirq"), state.event, true);
@@ -1508,13 +1506,13 @@
mutex_unlock(&dpm_list_mtx);
- error = device_suspend_noirq(dev, state, false);
+ device_suspend_noirq(dev, state, false);
put_device(dev);
mutex_lock(&dpm_list_mtx);
- if (error || async_error) {
+ if (READ_ONCE(async_error)) {
dpm_async_suspend_complete_all(&dpm_late_early_list);
/*
* Move all devices to the target list to resume them
@@ -1528,9 +1526,8 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
- if (!error)
- error = async_error;
+ error = READ_ONCE(async_error);
if (error)
dpm_save_failed_step(SUSPEND_SUSPEND_NOIRQ);
@@ -1585,7 +1582,7 @@
*
* Runtime PM is disabled for @dev while this function is being executed.
*/
-static int device_suspend_late(struct device *dev, pm_message_t state, bool async)
+static void device_suspend_late(struct device *dev, pm_message_t state, bool async)
{
pm_callback_t callback = NULL;
const char *info = NULL;
@@ -1602,11 +1599,11 @@
dpm_wait_for_subordinate(dev, async);
- if (async_error)
+ if (READ_ONCE(async_error))
goto Complete;
if (pm_wakeup_pending()) {
- async_error = -EBUSY;
+ WRITE_ONCE(async_error, -EBUSY);
goto Complete;
}
@@ -1640,7 +1637,7 @@
Run:
error = dpm_run_callback(callback, dev, state, info);
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async late" : " late", error);
goto Complete;
@@ -1654,12 +1651,10 @@
TRACE_SUSPEND(error);
complete_all(&dev->power.completion);
- if (error || async_error)
- return error;
+ if (error || READ_ONCE(async_error))
+ return;
dpm_async_suspend_superior(dev, async_suspend_late);
-
- return 0;
}
static void async_suspend_late(void *data, async_cookie_t cookie)
@@ -1678,7 +1673,7 @@
{
ktime_t starttime = ktime_get();
struct device *dev;
- int error = 0;
+ int error;
trace_suspend_resume(TPS("dpm_suspend_late"), state.event, true);
@@ -1711,13 +1706,13 @@
mutex_unlock(&dpm_list_mtx);
- error = device_suspend_late(dev, state, false);
+ device_suspend_late(dev, state, false);
put_device(dev);
mutex_lock(&dpm_list_mtx);
- if (error || async_error) {
+ if (READ_ONCE(async_error)) {
dpm_async_suspend_complete_all(&dpm_suspended_list);
/*
* Move all devices to the target list to resume them
@@ -1731,9 +1726,8 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
- if (!error)
- error = async_error;
+ error = READ_ONCE(async_error);
if (error) {
dpm_save_failed_step(SUSPEND_SUSPEND_LATE);
dpm_resume_early(resume_event(state));
@@ -1822,7 +1816,7 @@
* @state: PM transition of the system being carried out.
* @async: If true, the device is being suspended asynchronously.
*/
-static int device_suspend(struct device *dev, pm_message_t state, bool async)
+static void device_suspend(struct device *dev, pm_message_t state, bool async)
{
pm_callback_t callback = NULL;
const char *info = NULL;
@@ -1834,7 +1828,7 @@
dpm_wait_for_subordinate(dev, async);
- if (async_error) {
+ if (READ_ONCE(async_error)) {
dev->power.direct_complete = false;
goto Complete;
}
@@ -1854,7 +1848,7 @@
if (pm_wakeup_pending()) {
dev->power.direct_complete = false;
- async_error = -EBUSY;
+ WRITE_ONCE(async_error, -EBUSY);
goto Complete;
}
@@ -1938,7 +1932,7 @@
Complete:
if (error) {
- async_error = error;
+ WRITE_ONCE(async_error, error);
dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, async ? " async" : "", error);
}
@@ -1946,12 +1940,10 @@
complete_all(&dev->power.completion);
TRACE_SUSPEND(error);
- if (error || async_error)
- return error;
+ if (error || READ_ONCE(async_error))
+ return;
dpm_async_suspend_superior(dev, async_suspend);
-
- return 0;
}
static void async_suspend(void *data, async_cookie_t cookie)
@@ -1970,7 +1962,7 @@
{
ktime_t starttime = ktime_get();
struct device *dev;
- int error = 0;
+ int error;
trace_suspend_resume(TPS("dpm_suspend"), state.event, true);
might_sleep();
@@ -2005,13 +1997,13 @@
mutex_unlock(&dpm_list_mtx);
- error = device_suspend(dev, state, false);
+ device_suspend(dev, state, false);
put_device(dev);
mutex_lock(&dpm_list_mtx);
- if (error || async_error) {
+ if (READ_ONCE(async_error)) {
dpm_async_suspend_complete_all(&dpm_prepared_list);
/*
* Move all devices to the target list to resume them
@@ -2025,9 +2017,8 @@
mutex_unlock(&dpm_list_mtx);
async_synchronize_full();
- if (!error)
- error = async_error;
+ error = READ_ONCE(async_error);
if (error)
dpm_save_failed_step(SUSPEND_SUSPEND);
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