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linux-2.6
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Add support for suspending and resuming the whole console subsystem 

Trying to suspend/resume with console messages flying all around is
doomed to failure, when the devices that the messages are trying to
go to are being shut down.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Linus Torvalds 2006-06-19 18:16:01 -07:00
parent 5603509137
commit 557240b48e
3 changed files with 33 additions and 1 deletions
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4
include/linux/console.h
View File

@ -117,6 +117,10 @@ extern void console_stop(struct console *);
extern void console_start(struct console *);
extern int is_console_locked(void);
/* Suspend and resume console messages over PM events */
extern void suspend_console(void);
extern void resume_console(void);
/* Some debug stub to catch some of the obvious races in the VT code */
#if 1
#define WARN_CONSOLE_UNLOCKED() WARN_ON(!is_console_locked() && !oops_in_progress)

2
kernel/power/main.c
View File

@ -86,6 +86,7 @@ static int suspend_prepare(suspend_state_t state)
goto Thaw;
}
suspend_console();
if ((error = device_suspend(PMSG_SUSPEND))) {
printk(KERN_ERR "Some devices failed to suspend\n");
goto Finish;
@ -133,6 +134,7 @@ int suspend_enter(suspend_state_t state)
static void suspend_finish(suspend_state_t state)
{
device_resume();
resume_console();
thaw_processes();
enable_nonboot_cpus();
if (pm_ops && pm_ops->finish)

28
kernel/printk.c
View File

@ -67,6 +67,7 @@ EXPORT_SYMBOL(oops_in_progress);
* driver system.
*/
static DECLARE_MUTEX(console_sem);
static DECLARE_MUTEX(secondary_console_sem);
struct console *console_drivers;
/*
* This is used for debugging the mess that is the VT code by
@ -76,7 +77,7 @@ struct console *console_drivers;
* path in the console code where we end up in places I want
* locked without the console sempahore held
*/
static int console_locked;
static int console_locked, console_suspended;
/*
* logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
@ -697,6 +698,23 @@ int __init add_preferred_console(char *name, int idx, char *options)
return 0;
}
/**
* suspend_console - suspend the console subsystem
*
* This disables printk() while we go into suspend states
*/
void suspend_console(void)
{
acquire_console_sem();
console_suspended = 1;
}
void resume_console(void)
{
console_suspended = 0;
release_console_sem();
}
/**
* acquire_console_sem - lock the console system for exclusive use.
*
@ -708,6 +726,10 @@ int __init add_preferred_console(char *name, int idx, char *options)
void acquire_console_sem(void)
{
BUG_ON(in_interrupt());
if (console_suspended) {
down(&secondary_console_sem);
return;
}
down(&console_sem);
console_locked = 1;
console_may_schedule = 1;
@ -750,6 +772,10 @@ void release_console_sem(void)
unsigned long _con_start, _log_end;
unsigned long wake_klogd = 0;
if (console_suspended) {
up(&secondary_console_sem);
return;
}
for ( ; ; ) {
spin_lock_irqsave(&logbuf_lock, flags);
wake_klogd |= log_start - log_end;