[PATCH v2 08/10] PM: sleep: Move some assignments from under a lock

From: Rafael J. Wysocki
Date: Mon Jan 29 2024 - 11:36:55 EST


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

The async_error and pm_transition variables are set under dpm_list_mtx
in multiple places in the system-wide device PM core code, which is
unnecessary and confusing, so rearrange the code so that the variables
in question are set before acquiring the lock.

While at it, add some empty code lines around locking to improve the
consistency of the code.

No intentional functional impact.

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

v1 -> v2: No changes.

---
drivers/base/power/main.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)

Index: linux-pm/drivers/base/power/main.c
===================================================================
--- linux-pm.orig/drivers/base/power/main.c
+++ linux-pm/drivers/base/power/main.c
@@ -707,9 +707,9 @@ static void dpm_noirq_resume_devices(pm_
trace_suspend_resume(TPS("dpm_resume_noirq"), state.event, true);

async_error = 0;
+ pm_transition = state;

mutex_lock(&dpm_list_mtx);
- pm_transition = state;

/*
* Trigger the resume of "async" devices upfront so they don't have to
@@ -847,9 +847,9 @@ void dpm_resume_early(pm_message_t state
trace_suspend_resume(TPS("dpm_resume_early"), state.event, true);

async_error = 0;
+ pm_transition = state;

mutex_lock(&dpm_list_mtx);
- pm_transition = state;

/*
* Trigger the resume of "async" devices upfront so they don't have to
@@ -1012,10 +1012,11 @@ void dpm_resume(pm_message_t state)
trace_suspend_resume(TPS("dpm_resume"), state.event, true);
might_sleep();

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

+ mutex_lock(&dpm_list_mtx);
+
/*
* Trigger the resume of "async" devices upfront so they don't have to
* wait for the "non-async" ones they don't depend on.
@@ -1294,10 +1295,12 @@ static int dpm_noirq_suspend_devices(pm_
int error = 0;

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

+ mutex_lock(&dpm_list_mtx);
+
while (!list_empty(&dpm_late_early_list)) {
struct device *dev = to_device(dpm_late_early_list.prev);

@@ -1320,7 +1323,9 @@ static int dpm_noirq_suspend_devices(pm_
if (error || async_error)
break;
}
+
mutex_unlock(&dpm_list_mtx);
+
async_synchronize_full();
if (!error)
error = async_error;
@@ -1470,11 +1475,14 @@ int dpm_suspend_late(pm_message_t state)
int error = 0;

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

+ wake_up_all_idle_cpus();
+
+ mutex_lock(&dpm_list_mtx);
+
while (!list_empty(&dpm_suspended_list)) {
struct device *dev = to_device(dpm_suspended_list.prev);

@@ -1498,7 +1506,9 @@ int dpm_suspend_late(pm_message_t state)
if (error || async_error)
break;
}
+
mutex_unlock(&dpm_list_mtx);
+
async_synchronize_full();
if (!error)
error = async_error;
@@ -1745,9 +1755,11 @@ int dpm_suspend(pm_message_t state)
devfreq_suspend();
cpufreq_suspend();

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

@@ -1771,7 +1783,9 @@ int dpm_suspend(pm_message_t state)
if (error || async_error)
break;
}
+
mutex_unlock(&dpm_list_mtx);
+
async_synchronize_full();
if (!error)
error = async_error;