freezer: Have {,un}lock_system_sleep() save/restore flags

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@infradead.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20220822114648.725003428@infradead.org

Author: Peter Zijlstra

drivers/acpi/x86/s2idle.c

@@ -541,25 +541,29 @@ 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;
 }
 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);
 

drivers/scsi/scsi_transport_spi.c

@@ -998,16 +998,17 @@ 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
 	 * scsi_device_quiesce(), it is not safe to perform domain validation
 	 * 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);
 

include/linux/suspend.h

@@ -510,8 +510,8 @@ extern bool pm_save_wakeup_count(unsigned int count);
 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 */
 

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);
 
@@ -713,14 +717,15 @@ static int load_image_and_restore(void)
 int hibernate(void)
 {
 	bool snapshot_test = false;
+	unsigned int sleep_flags;
 	int error;
 
 	if (!hibernation_available()) {
 		pm_pr_dbg("Hibernation not available.\n");
 		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)(void *data), void *data)
 	hibernate_release();
 
 unlock:
-	unlock_system_sleep();
+	unlock_system_sleep(sleep_flags);
 
 	return error;
 }
@@ -1100,19 +1106,20 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
 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;
 
 	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 *kobj, struct kobj_attribute *attr,
 	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 kobject *kobj, struct kobj_attribute *attr,
 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 kobject *kobj, struct kobj_attribute *attr,
 	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;

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);
@@ -263,16 +266,17 @@ static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
 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++)
@@ -282,7 +286,7 @@ static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
 			break;
 		}
 
-	unlock_system_sleep();
+	unlock_system_sleep(sleep_flags);
 
 	return error ? error : n;
 }

kernel/power/suspend.c

@@ -75,9 +75,11 @@ EXPORT_SYMBOL_GPL(pm_suspend_default_s2idle);
 
 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_default_setup);
  */
 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 platform_suspend_ops *ops)
 			mem_sleep_current = PM_SUSPEND_MEM;
 	}
 
-	unlock_system_sleep();
+	unlock_system_sleep(sleep_flags);
 }
 EXPORT_SYMBOL_GPL(suspend_set_ops);