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Commit 557240b4 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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: default avatarLinus Torvalds <torvalds@osdl.org>
parent 56035091
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+4 −0
Original line number Diff line number Diff line
@@ -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 −0
Original line number Diff line number Diff line
@@ -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)
+27 −1
Original line number Diff line number Diff line
@@ -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;