[RFC][PATCH] PM: Use suspend_console in swsusp and make it configureable

Rafael J. Wysocki
2006-08-15T13:09:05Z

Hi,

The appended patch does the following:

1) Adds suspend_console() and resume_console() to the suspend-to-disk code
paths so that people using netconsole are safe with swsusp.

2) Adds a Kconfig option allowing us to disable suspend_/resume_console()
if need be.

3) Marks CONFIG_PM_TRACE as dangerous.

Comments welcome.

Greetings,
Rafael

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
include/linux/console.h | 5 +++++
kernel/power/Kconfig | 13 ++++++++++++-
kernel/power/disk.c | 8 ++++++++
kernel/power/user.c | 8 +++++++-
kernel/printk.c | 2 ++
5 files changed, 34 insertions(+), 2 deletions(-)

Index: linux-2.6.18-rc4-mm1/kernel/power/disk.c
===================================================================
--- linux-2.6.18-rc4-mm1.orig/kernel/power/disk.c
+++ linux-2.6.18-rc4-mm1/kernel/power/disk.c
@@ -18,6 +18,7 @@
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pm.h>
+#include <linux/console.h>
#include <linux/cpu.h>

#include "power.h"
@@ -119,8 +120,10 @@ int pm_suspend_disk(void)
if (error)
return error;

+ suspend_console();
error = device_suspend(PMSG_FREEZE);
if (error) {
+ resume_console();
printk("Some devices failed to suspend\n");
unprepare_processes();
return error;
@@ -133,6 +136,7 @@ int pm_suspend_disk(void)

if (in_suspend) {
device_resume();
+ resume_console();
pr_debug("PM: writing image.\n");
error = swsusp_write();
if (!error)
@@ -148,6 +152,7 @@ int pm_suspend_disk(void)
swsusp_free();
Done:
device_resume();
+ resume_console();
unprepare_processes();
return error;
}
@@ -212,7 +217,9 @@ static int software_resume(void)

pr_debug("PM: Preparing devices for restore.\n");

+ suspend_console();
if ((error = device_suspend(PMSG_PRETHAW))) {
+ resume_console();
printk("Some devices failed to suspend\n");
swsusp_free();
goto Thaw;
@@ -224,6 +231,7 @@ static int software_resume(void)
swsusp_resume();
pr_debug("PM: Restore failed, recovering.n");
device_resume();
+ resume_console();
Thaw:
unprepare_processes();
Done:
Index: linux-2.6.18-rc4-mm1/kernel/power/user.c
===================================================================
--- linux-2.6.18-rc4-mm1.orig/kernel/power/user.c
+++ linux-2.6.18-rc4-mm1/kernel/power/user.c
@@ -19,6 +19,7 @@
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/fs.h>
+#include <linux/console.h>
#include <linux/cpu.h>

#include <asm/uaccess.h>
@@ -173,12 +174,14 @@ static int snapshot_ioctl(struct inode *
/* Free memory before shutting down devices. */
error = swsusp_shrink_memory();
if (!error) {
+ suspend_console();
error = device_suspend(PMSG_FREEZE);
if (!error) {
in_suspend = 1;
error = swsusp_suspend();
device_resume();
}
+ resume_console();
}
up(&pm_sem);
if (!error)
@@ -196,11 +199,13 @@ static int snapshot_ioctl(struct inode *
}
down(&pm_sem);
pm_prepare_console();
+ suspend_console();
error = device_suspend(PMSG_PRETHAW);
if (!error) {
error = swsusp_resume();
device_resume();
}
+ resume_console();
pm_restore_console();
up(&pm_sem);
break;
@@ -289,6 +294,7 @@ static int snapshot_ioctl(struct inode *
}

/* Put devices to sleep */
+ suspend_console();
error = device_suspend(PMSG_SUSPEND);
if (error) {
printk(KERN_ERR "Failed to suspend some devices.\n");
@@ -299,7 +305,7 @@ static int snapshot_ioctl(struct inode *
/* Wake up devices */
device_resume();
}
-
+ resume_console();
if (pm_ops->finish)
pm_ops->finish(PM_SUSPEND_MEM);

Index: linux-2.6.18-rc4-mm1/include/linux/console.h
===================================================================
--- linux-2.6.18-rc4-mm1.orig/include/linux/console.h
+++ linux-2.6.18-rc4-mm1/include/linux/console.h
@@ -120,9 +120,14 @@ extern void console_stop(struct console
extern void console_start(struct console *);
extern int is_console_locked(void);

+#ifndef CONFIG_PM_DISABLE_CONSOLE_SUSPEND
/* Suspend and resume console messages over PM events */
extern void suspend_console(void);
extern void resume_console(void);
+#else
+static inline void suspend_console(void) {}
+static inline void resume_console(void) {}
+#endif /* CONFIG_PM_DISABLE_CONSOLE_SUSPEND */

/* Some debug stub to catch some of the obvious races in the VT code */
#if 1
Index: linux-2.6.18-rc4-mm1/kernel/power/Kconfig
===================================================================
--- linux-2.6.18-rc4-mm1.orig/kernel/power/Kconfig
+++ linux-2.6.18-rc4-mm1/kernel/power/Kconfig
@@ -36,8 +36,19 @@ config PM_DEBUG
code. This is helpful when debugging and reporting various PM bugs,
like suspend support.

+config PM_DISABLE_CONSOLE_SUSPEND
+ bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
+ depends on PM && PM_DEBUG
+ default n
+ ---help---
+ This option turns off the console suspend mechanism that prevents
+ debug messages from reaching the console during the suspend/resume
+ operations. This may be helpful when debugging device drivers'
+ suspend/resume routines, but may itself lead to problems, for example
+ if netconsole is used.
+
config PM_TRACE
- bool "Suspend/resume event tracing"
+ bool "Suspend/resume event tracing (DANGEROUS)"
depends on PM && PM_DEBUG && X86_32 && EXPERIMENTAL
default n
---help---
Index: linux-2.6.18-rc4-mm1/kernel/printk.c
===================================================================
--- linux-2.6.18-rc4-mm1.orig/kernel/printk.c
+++ linux-2.6.18-rc4-mm1/kernel/printk.c
@@ -702,6 +702,7 @@ int __init add_preferred_console(char *n
return 0;
}

+#ifndef CONFIG_PM_DISABLE_CONSOLE_SUSPEND
/**
* suspend_console - suspend the console subsystem
*
@@ -718,6 +719,7 @@ void resume_console(void)
console_suspended = 0;
release_console_sem();
}
+#endif /* CONFIG_PM_DISABLE_CONSOLE_SUSPEND */

/**
* acquire_console_sem - lock the console system for exclusive use.