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SubjectRe: [PATCH 3/3] PM / Hibernate: Update kerneldoc comments in hibernate.c
Date
On Monday, May 23, 2011, Randy Dunlap wrote:
> On 05/21/11 05:12, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > Some of the kerneldoc comments in kernel/power/hibernate.c are
> > outdated and some of them don't adhere to the kernel's standards.
> > Update them and make them look in a consistent way.
>
> Hi Rafael,

Hi,

> Several of the functions are missing function parameter notations, as
> noted below.

Ah, thanks! Those should be fixed in the new version of the patch below.

Thanks,
Rafael


---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM / Hibernate: Update kerneldoc comments in hibernate.c

Some of the kerneldoc comments in kernel/power/hibernate.c are
outdated and some of them don't adhere to the kernel's standards.
Update them and make them look in a consistent way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
kernel/power/hibernate.c | 194 +++++++++++++++++++++++++----------------------
1 file changed, 104 insertions(+), 90 deletions(-)

Index: linux-2.6/kernel/power/hibernate.c
===================================================================
--- linux-2.6.orig/kernel/power/hibernate.c
+++ linux-2.6/kernel/power/hibernate.c
@@ -55,10 +55,9 @@ static int hibernation_mode = HIBERNATIO
static const struct platform_hibernation_ops *hibernation_ops;

/**
- * hibernation_set_ops - set the global hibernate operations
- * @ops: the hibernation operations to use in subsequent hibernation transitions
+ * hibernation_set_ops - Set the global hibernate operations.
+ * @ops: Hibernation operations to use in subsequent hibernation transitions.
*/
-
void hibernation_set_ops(const struct platform_hibernation_ops *ops)
{
if (ops && !(ops->begin && ops->end && ops->pre_snapshot
@@ -115,10 +114,9 @@ static int hibernation_test(int level) {
#endif /* !CONFIG_PM_DEBUG */

/**
- * platform_begin - tell the platform driver that we're starting
- * hibernation
+ * platform_begin - Call platform to start hibernation.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static int platform_begin(int platform_mode)
{
return (platform_mode && hibernation_ops) ?
@@ -126,10 +124,9 @@ static int platform_begin(int platform_m
}

/**
- * platform_end - tell the platform driver that we've entered the
- * working state
+ * platform_end - Call platform to finish transition to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static void platform_end(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -137,8 +134,11 @@ static void platform_end(int platform_mo
}

/**
- * platform_pre_snapshot - prepare the machine for hibernation using the
- * platform driver if so configured and return an error code if it fails
+ * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to prepare the system for creating a hibernate image,
+ * if so configured, and return an error code if that fails.
*/

static int platform_pre_snapshot(int platform_mode)
@@ -148,10 +148,14 @@ static int platform_pre_snapshot(int pla
}

/**
- * platform_leave - prepare the machine for switching to the normal mode
- * of operation using the platform driver (called with interrupts disabled)
+ * platform_leave - Call platform to prepare a transition to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver prepare to prepare the machine for switching to the
+ * normal mode of operation.
+ *
+ * This routine is called on one CPU with interrupts disabled.
*/
-
static void platform_leave(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -159,10 +163,14 @@ static void platform_leave(int platform_
}

/**
- * platform_finish - switch the machine to the normal mode of operation
- * using the platform driver (must be called after platform_prepare())
+ * platform_finish - Call platform to switch the system to the working state.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to switch the machine to the normal mode of
+ * operation.
+ *
+ * This routine must be called after platform_prepare().
*/
-
static void platform_finish(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -170,11 +178,15 @@ static void platform_finish(int platform
}

/**
- * platform_pre_restore - prepare the platform for the restoration from a
- * hibernation image. If the restore fails after this function has been
- * called, platform_restore_cleanup() must be called.
+ * platform_pre_restore - Prepare for hibernate image restoration.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to prepare the system for resume from a hibernation
+ * image.
+ *
+ * If the restore fails after this function has been called,
+ * platform_restore_cleanup() must be called.
*/
-
static int platform_pre_restore(int platform_mode)
{
return (platform_mode && hibernation_ops) ?
@@ -182,12 +194,16 @@ static int platform_pre_restore(int plat
}

/**
- * platform_restore_cleanup - switch the platform to the normal mode of
- * operation after a failing restore. If platform_pre_restore() has been
- * called before the failing restore, this function must be called too,
- * regardless of the result of platform_pre_restore().
+ * platform_restore_cleanup - Switch to the working state after failing restore.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Use the platform driver to switch the system to the normal mode of operation
+ * after a failing restore.
+ *
+ * If platform_pre_restore() has been called before the failing restore, this
+ * function must be called too, regardless of the result of
+ * platform_pre_restore().
*/
-
static void platform_restore_cleanup(int platform_mode)
{
if (platform_mode && hibernation_ops)
@@ -195,10 +211,9 @@ static void platform_restore_cleanup(int
}

/**
- * platform_recover - recover the platform from a failure to suspend
- * devices.
+ * platform_recover - Recover from a failure to suspend devices.
+ * @platform_mode: Whether or not to use the platform driver.
*/
-
static void platform_recover(int platform_mode)
{
if (platform_mode && hibernation_ops && hibernation_ops->recover)
@@ -206,13 +221,12 @@ static void platform_recover(int platfor
}

/**
- * swsusp_show_speed - print the time elapsed between two events.
- * @start: Starting event.
- * @stop: Final event.
- * @nr_pages - number of pages processed between @start and @stop
- * @msg - introductory message to print
+ * swsusp_show_speed - Print time elapsed between two events during hibernation.
+ * @start: Starting event.
+ * @stop: Final event.
+ * @nr_pages: Number of memory pages processed between @start and @stop.
+ * @msg: Additional diagnostic message to print.
*/
-
void swsusp_show_speed(struct timeval *start, struct timeval *stop,
unsigned nr_pages, char *msg)
{
@@ -235,11 +249,14 @@ void swsusp_show_speed(struct timeval *s
}

/**
- * create_image - freeze devices that need to be frozen with interrupts
- * off, create the hibernation image and thaw those devices. Control
- * reappears in this routine after a restore.
+ * create_image - Create a hibernation image.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Execute device drivers' .freeze_noirq() callbacks, create a hibernation image
+ * and execute the drivers' .thaw_noirq() callbacks.
+ *
+ * Control reappears in this routine after the subsequent restore.
*/
-
static int create_image(int platform_mode)
{
int error;
@@ -304,14 +321,11 @@ static int create_image(int platform_mod
}

/**
- * hibernation_snapshot - quiesce devices and create the hibernation
- * snapshot image.
- * @platform_mode - if set, use the platform driver, if available, to
- * prepare the platform firmware for the power transition.
+ * hibernation_snapshot - Quiesce devices and create a hibernation image.
+ * @platform_mode: If set, use platform driver to prepare for the transition.
*
- * Must be called with pm_mutex held
+ * This routine must be called with pm_mutex held.
*/
-
int hibernation_snapshot(int platform_mode)
{
pm_message_t msg = PMSG_RECOVER;
@@ -371,13 +385,14 @@ int hibernation_snapshot(int platform_mo
}

/**
- * resume_target_kernel - prepare devices that need to be suspended with
- * interrupts off, restore the contents of highmem that have not been
- * restored yet from the image and run the low level code that will restore
- * the remaining contents of memory and switch to the just restored target
- * kernel.
+ * resume_target_kernel - Restore system state from a hibernation image.
+ * @platform_mode: Whether or not to use the platform driver.
+ *
+ * Execute device drivers' .freeze_noirq() callbacks, restore the contents of
+ * highmem that have not been restored yet from the image and run the low-level
+ * code that will restore the remaining contents of memory and switch to the
+ * just restored target kernel.
*/
-
static int resume_target_kernel(bool platform_mode)
{
int error;
@@ -445,14 +460,12 @@ static int resume_target_kernel(bool pla
}

/**
- * hibernation_restore - quiesce devices and restore the hibernation
- * snapshot image. If successful, control returns in hibernation_snaphot()
- * @platform_mode - if set, use the platform driver, if available, to
- * prepare the platform firmware for the transition.
+ * hibernation_restore - Quiesce devices and restore from a hibernation image.
+ * @platform_mode: If set, use platform driver to prepare for the transition.
*
- * Must be called with pm_mutex held
+ * This routine must be called with pm_mutex held. If it is successful, control
+ * reappears in the restored target kernel in hibernation_snaphot().
*/
-
int hibernation_restore(int platform_mode)
{
int error;
@@ -472,10 +485,8 @@ int hibernation_restore(int platform_mod
}

/**
- * hibernation_platform_enter - enter the hibernation state using the
- * platform driver (if available)
+ * hibernation_platform_enter - Power off the system using the platform driver.
*/
-
int hibernation_platform_enter(void)
{
int error;
@@ -546,12 +557,12 @@ int hibernation_platform_enter(void)
}

/**
- * power_down - Shut the machine down for hibernation.
+ * power_down - Shut the machine down for hibernation.
*
- * Use the platform driver, if configured so; otherwise try
- * to power off or reboot.
+ * Use the platform driver, if configured, to put the system into the sleep
+ * state corresponding to hibernation, or try to power it off or reboot,
+ * depending on the value of hibernation_mode.
*/
-
static void power_down(void)
{
switch (hibernation_mode) {
@@ -588,9 +599,8 @@ static int prepare_processes(void)
}

/**
- * hibernate - The granpappy of the built-in hibernation management
+ * hibernate - Carry out system hibernation, including saving the image.
*/
-
int hibernate(void)
{
int error;
@@ -668,17 +678,20 @@ int hibernate(void)


/**
- * software_resume - Resume from a saved image.
+ * software_resume - Resume from a saved hibernation image.
+ *
+ * This routine is called as a late initcall, when all devices have been
+ * discovered and initialized already.
*
- * Called as a late_initcall (so all devices are discovered and
- * initialized), we call swsusp to see if we have a saved image or not.
- * If so, we quiesce devices, the restore the saved image. We will
- * return above (in hibernate() ) if everything goes well.
- * Otherwise, we fail gracefully and return to the normally
- * scheduled program.
+ * The image reading code is called to see if there is a hibernation image
+ * available for reading. If that is the case, devices are quiesced and the
+ * contents of memory is restored from the saved image.
*
+ * If this is successful, control reappears in the restored target kernel in
+ * hibernation_snaphot() which returns to hibernate(). Otherwise, the routine
+ * attempts to recover gracefully and make the kernel return to the normal mode
+ * of operation.
*/
-
static int software_resume(void)
{
int error;
@@ -808,21 +821,17 @@ static const char * const hibernation_mo
[HIBERNATION_TESTPROC] = "testproc",
};

-/**
- * disk - Control hibernation mode
+/*
+ * /sys/power/disk - Control hibernation mode.
*
- * Suspend-to-disk can be handled in several ways. We have a few options
- * for putting the system to sleep - using the platform driver (e.g. ACPI
- * or other hibernation_ops), powering off the system or rebooting the
- * system (for testing) as well as the two test modes.
- *
- * The system can support 'platform', and that is known a priori (and
- * encoded by the presence of hibernation_ops). However, the user may
- * choose 'shutdown' or 'reboot' as alternatives, as well as one fo the
- * test modes, 'test' or 'testproc'.
+ * Hibernation can be handled in several ways. There are a few different ways
+ * to put the system into the sleep state: using the platform driver (e.g. ACPI
+ * or other hibernation_ops), powering it off or rebooting it (for testing
+ * mostly), or using one of the two available test modes.
*
- * show() will display what the mode is currently set to.
- * store() will accept one of
+ * The sysfs file /sys/power/disk provides an interface for selecting the
+ * hibernation mode to use. Reading from this file causes the available modes
+ * to be printed. There are 5 modes that can be supported:
*
* 'platform'
* 'shutdown'
@@ -830,8 +839,14 @@ static const char * const hibernation_mo
* 'test'
* 'testproc'
*
- * It will only change to 'platform' if the system
- * supports it (as determined by having hibernation_ops).
+ * If a platform hibernation driver is in use, 'platform' will be supported
+ * and will be used by default. Otherwise, 'shutdown' will be used by default.
+ * The selected option (i.e. the one corresponding to the current value of
+ * hibernation_mode) is enclosed by a square bracket.
+ *
+ * To select a given hibernation mode it is necessary to write the mode's
+ * string representation (as returned by reading from /sys/power/disk) back
+ * into /sys/power/disk.
*/

static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
@@ -864,7 +879,6 @@ static ssize_t disk_show(struct kobject
return buf-start;
}

-
static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t n)
{

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