[PATCH 3/5] freezer: Have {,un}lock_system_sleep() save/restore flags

From: Peter Zijlstra
Date: Tue Apr 12 2022 - 08:31:36 EST

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Rafael explained that the reason for having both PF_NOFREEZE and
PF_FREEZER_SKIP is that {,un}lock_system_sleep() is callable from
kthread context that has previously called set_freezable().

In preparation of merging the flags, have {,un}lock_system_slee() save
and restore current->flags.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
drivers/acpi/x86/s2idle.c | 12 ++++++++----
drivers/scsi/scsi_transport_spi.c | 7 ++++---
include/linux/suspend.h | 8 ++++----
kernel/power/hibernate.c | 35 ++++++++++++++++++++++-------------
kernel/power/main.c | 16 ++++++++++------
kernel/power/suspend.c | 12 ++++++++----
kernel/power/user.c | 24 ++++++++++++++----------
7 files changed, 70 insertions(+), 44 deletions(-)

--- a/drivers/acpi/x86/s2idle.c
+++ b/drivers/acpi/x86/s2idle.c
@@ -538,12 +538,14 @@ void acpi_s2idle_setup(void)

int acpi_register_lps0_dev(struct acpi_s2idle_dev_ops *arg)
{
+ unsigned int sleep_flags;
+
if (!lps0_device_handle || sleep_no_lps0)
return -ENODEV;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();
list_add(&arg->list_node, &lps0_s2idle_devops_head);
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return 0;
}
@@ -551,12 +553,14 @@ EXPORT_SYMBOL_GPL(acpi_register_lps0_dev

void acpi_unregister_lps0_dev(struct acpi_s2idle_dev_ops *arg)
{
+ unsigned int sleep_flags;
+
if (!lps0_device_handle || sleep_no_lps0)
return;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();
list_del(&arg->list_node);
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
}
EXPORT_SYMBOL_GPL(acpi_unregister_lps0_dev);

--- a/drivers/scsi/scsi_transport_spi.c
+++ b/drivers/scsi/scsi_transport_spi.c
@@ -998,8 +998,9 @@ void
spi_dv_device(struct scsi_device *sdev)
{
struct scsi_target *starget = sdev->sdev_target;
- u8 *buffer;
const int len = SPI_MAX_ECHO_BUFFER_SIZE*2;
+ unsigned int sleep_flags;
+ u8 *buffer;

/*
* Because this function and the power management code both call
@@ -1007,7 +1008,7 @@ spi_dv_device(struct scsi_device *sdev)
* while suspend or resume is in progress. Hence the
* lock/unlock_system_sleep() calls.
*/
- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

if (scsi_autopm_get_device(sdev))
goto unlock_system_sleep;
@@ -1058,7 +1059,7 @@ spi_dv_device(struct scsi_device *sdev)
scsi_autopm_put_device(sdev);

unlock_system_sleep:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
}
EXPORT_SYMBOL(spi_dv_device);

--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -510,8 +510,8 @@ extern bool pm_save_wakeup_count(unsigne
extern void pm_wakep_autosleep_enabled(bool set);
extern void pm_print_active_wakeup_sources(void);

-extern void lock_system_sleep(void);
-extern void unlock_system_sleep(void);
+extern unsigned int lock_system_sleep(void);
+extern void unlock_system_sleep(unsigned int);

#else /* !CONFIG_PM_SLEEP */

@@ -534,8 +534,8 @@ static inline void pm_system_wakeup(void
static inline void pm_wakeup_clear(bool reset) {}
static inline void pm_system_irq_wakeup(unsigned int irq_number) {}

-static inline void lock_system_sleep(void) {}
-static inline void unlock_system_sleep(void) {}
+static inline unsigned int lock_system_sleep(void) { return 0; }
+static inline void unlock_system_sleep(unsigned int flags) {}

#endif /* !CONFIG_PM_SLEEP */

--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -92,20 +92,24 @@ bool hibernation_available(void)
*/
void hibernation_set_ops(const struct platform_hibernation_ops *ops)
{
+ unsigned int sleep_flags;
+
if (ops && !(ops->begin && ops->end && ops->pre_snapshot
&& ops->prepare && ops->finish && ops->enter && ops->pre_restore
&& ops->restore_cleanup && ops->leave)) {
WARN_ON(1);
return;
}
- lock_system_sleep();
+
+ sleep_flags = lock_system_sleep();
+
hibernation_ops = ops;
if (ops)
hibernation_mode = HIBERNATION_PLATFORM;
else if (hibernation_mode == HIBERNATION_PLATFORM)
hibernation_mode = HIBERNATION_SHUTDOWN;

- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
}
EXPORT_SYMBOL_GPL(hibernation_set_ops);

@@ -713,6 +717,7 @@ static int load_image_and_restore(void)
int hibernate(void)
{
bool snapshot_test = false;
+ unsigned int sleep_flags;
int error;

if (!hibernation_available()) {
@@ -720,7 +725,7 @@ int hibernate(void)
return -EPERM;
}

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();
/* The snapshot device should not be opened while we're running */
if (!hibernate_acquire()) {
error = -EBUSY;
@@ -794,7 +799,7 @@ int hibernate(void)
pm_restore_console();
hibernate_release();
Unlock:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
pr_info("hibernation exit\n");

return error;
@@ -809,9 +814,10 @@ int hibernate(void)
*/
int hibernate_quiet_exec(int (*func)(void *data), void *data)
{
+ unsigned int sleep_flags;
int error;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

if (!hibernate_acquire()) {
error = -EBUSY;
@@ -891,7 +897,7 @@ int hibernate_quiet_exec(int (*func)(voi
hibernate_release();

unlock:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return error;
}
@@ -1100,11 +1106,12 @@ static ssize_t disk_show(struct kobject
static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t n)
{
+ int mode = HIBERNATION_INVALID;
+ unsigned int sleep_flags;
int error = 0;
- int i;
int len;
char *p;
- int mode = HIBERNATION_INVALID;
+ int i;

if (!hibernation_available())
return -EPERM;
@@ -1112,7 +1119,7 @@ static ssize_t disk_store(struct kobject
p = memchr(buf, '\n', n);
len = p ? p - buf : n;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();
for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
if (len == strlen(hibernation_modes[i])
&& !strncmp(buf, hibernation_modes[i], len)) {
@@ -1142,7 +1149,7 @@ static ssize_t disk_store(struct kobject
if (!error)
pm_pr_dbg("Hibernation mode set to '%s'\n",
hibernation_modes[mode]);
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
return error ? error : n;
}

@@ -1158,9 +1165,10 @@ static ssize_t resume_show(struct kobjec
static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t n)
{
- dev_t res;
+ unsigned int sleep_flags;
int len = n;
char *name;
+ dev_t res;

if (len && buf[len-1] == '\n')
len--;
@@ -1173,9 +1181,10 @@ static ssize_t resume_store(struct kobje
if (!res)
return -EINVAL;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();
swsusp_resume_device = res;
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
+
pm_pr_dbg("Configured hibernation resume from disk to %u\n",
swsusp_resume_device);
noresume = 0;
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -21,14 +21,16 @@

#ifdef CONFIG_PM_SLEEP

-void lock_system_sleep(void)
+unsigned int lock_system_sleep(void)
{
+ unsigned int flags = current->flags;
current->flags |= PF_FREEZER_SKIP;
mutex_lock(&system_transition_mutex);
+ return flags;
}
EXPORT_SYMBOL_GPL(lock_system_sleep);

-void unlock_system_sleep(void)
+void unlock_system_sleep(unsigned int flags)
{
/*
* Don't use freezer_count() because we don't want the call to
@@ -46,7 +48,8 @@ void unlock_system_sleep(void)
* Which means, if we use try_to_freeze() here, it would make them
* enter the refrigerator, thus causing hibernation to lockup.
*/
- current->flags &= ~PF_FREEZER_SKIP;
+ if (!(flags & PF_FREEZER_SKIP))
+ current->flags &= ~PF_FREEZER_SKIP;
mutex_unlock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(unlock_system_sleep);
@@ -260,16 +263,17 @@ static ssize_t pm_test_show(struct kobje
static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t n)
{
+ unsigned int sleep_flags;
const char * const *s;
+ int error = -EINVAL;
int level;
char *p;
int len;
- int error = -EINVAL;

p = memchr(buf, '\n', n);
len = p ? p - buf : n;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

level = TEST_FIRST;
for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
@@ -279,7 +283,7 @@ static ssize_t pm_test_store(struct kobj
break;
}

- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return error ? error : n;
}
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -75,9 +75,11 @@ EXPORT_SYMBOL_GPL(pm_suspend_default_s2i

void s2idle_set_ops(const struct platform_s2idle_ops *ops)
{
- lock_system_sleep();
+ unsigned int sleep_flags;
+
+ sleep_flags = lock_system_sleep();
s2idle_ops = ops;
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
}

static void s2idle_begin(void)
@@ -200,7 +202,9 @@ __setup("mem_sleep_default=", mem_sleep_
*/
void suspend_set_ops(const struct platform_suspend_ops *ops)
{
- lock_system_sleep();
+ unsigned int sleep_flags;
+
+ sleep_flags = lock_system_sleep();

suspend_ops = ops;

@@ -216,7 +220,7 @@ void suspend_set_ops(const struct platfo
mem_sleep_current = PM_SUSPEND_MEM;
}

- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);
}
EXPORT_SYMBOL_GPL(suspend_set_ops);

--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -46,12 +46,13 @@ int is_hibernate_resume_dev(dev_t dev)
static int snapshot_open(struct inode *inode, struct file *filp)
{
struct snapshot_data *data;
+ unsigned int sleep_flags;
int error;

if (!hibernation_available())
return -EPERM;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

if (!hibernate_acquire()) {
error = -EBUSY;
@@ -97,7 +98,7 @@ static int snapshot_open(struct inode *i
data->dev = 0;

Unlock:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return error;
}
@@ -105,8 +106,9 @@ static int snapshot_open(struct inode *i
static int snapshot_release(struct inode *inode, struct file *filp)
{
struct snapshot_data *data;
+ unsigned int sleep_flags;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

swsusp_free();
data = filp->private_data;
@@ -123,7 +125,7 @@ static int snapshot_release(struct inode
PM_POST_HIBERNATION : PM_POST_RESTORE);
hibernate_release();

- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return 0;
}
@@ -131,11 +133,12 @@ static int snapshot_release(struct inode
static ssize_t snapshot_read(struct file *filp, char __user *buf,
size_t count, loff_t *offp)
{
+ loff_t pg_offp = *offp & ~PAGE_MASK;
struct snapshot_data *data;
+ unsigned int sleep_flags;
ssize_t res;
- loff_t pg_offp = *offp & ~PAGE_MASK;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

data = filp->private_data;
if (!data->ready) {
@@ -156,7 +159,7 @@ static ssize_t snapshot_read(struct file
*offp += res;

Unlock:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return res;
}
@@ -164,11 +167,12 @@ static ssize_t snapshot_read(struct file
static ssize_t snapshot_write(struct file *filp, const char __user *buf,
size_t count, loff_t *offp)
{
+ loff_t pg_offp = *offp & ~PAGE_MASK;
struct snapshot_data *data;
+ unsigned int sleep_flags;
ssize_t res;
- loff_t pg_offp = *offp & ~PAGE_MASK;

- lock_system_sleep();
+ sleep_flags = lock_system_sleep();

data = filp->private_data;

@@ -190,7 +194,7 @@ static ssize_t snapshot_write(struct fil
if (res > 0)
*offp += res;
unlock:
- unlock_system_sleep();
+ unlock_system_sleep(sleep_flags);

return res;
}

Next message: Krzysztof Hałasa: "Re: [PATCH v8 2/2] On Semi AR0521 sensor driver"
Previous message: Peter Zijlstra: "[PATCH 0/5] ptrace-vs-PREEMPT_RT and freezer rewrite"
In reply to: Peter Zijlstra: "[PATCH 0/5] ptrace-vs-PREEMPT_RT and freezer rewrite"
Next in thread: Peter Zijlstra: "[PATCH 5/5] freezer,sched: Rewrite core freezer logic"
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