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

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
...@@ -117,6 +117,10 @@ extern void console_stop(struct console *); ...@@ -117,6 +117,10 @@ extern void console_stop(struct console *);
extern void console_start(struct console *); extern void console_start(struct console *);
extern int is_console_locked(void); 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 */ /* Some debug stub to catch some of the obvious races in the VT code */
#if 1 #if 1
#define WARN_CONSOLE_UNLOCKED() WARN_ON(!is_console_locked() && !oops_in_progress) #define WARN_CONSOLE_UNLOCKED() WARN_ON(!is_console_locked() && !oops_in_progress)
......
...@@ -86,6 +86,7 @@ static int suspend_prepare(suspend_state_t state) ...@@ -86,6 +86,7 @@ static int suspend_prepare(suspend_state_t state)
goto Thaw; goto Thaw;
} }
suspend_console();
if ((error = device_suspend(PMSG_SUSPEND))) { if ((error = device_suspend(PMSG_SUSPEND))) {
printk(KERN_ERR "Some devices failed to suspend\n"); printk(KERN_ERR "Some devices failed to suspend\n");
goto Finish; goto Finish;
...@@ -133,6 +134,7 @@ int suspend_enter(suspend_state_t state) ...@@ -133,6 +134,7 @@ int suspend_enter(suspend_state_t state)
static void suspend_finish(suspend_state_t state) static void suspend_finish(suspend_state_t state)
{ {
device_resume(); device_resume();
resume_console();
thaw_processes(); thaw_processes();
enable_nonboot_cpus(); enable_nonboot_cpus();
if (pm_ops && pm_ops->finish) if (pm_ops && pm_ops->finish)
......
...@@ -67,6 +67,7 @@ EXPORT_SYMBOL(oops_in_progress); ...@@ -67,6 +67,7 @@ EXPORT_SYMBOL(oops_in_progress);
* driver system. * driver system.
*/ */
static DECLARE_MUTEX(console_sem); static DECLARE_MUTEX(console_sem);
static DECLARE_MUTEX(secondary_console_sem);
struct console *console_drivers; struct console *console_drivers;
/* /*
* This is used for debugging the mess that is the VT code by * This is used for debugging the mess that is the VT code by
...@@ -76,7 +77,7 @@ struct console *console_drivers; ...@@ -76,7 +77,7 @@ struct console *console_drivers;
* path in the console code where we end up in places I want * path in the console code where we end up in places I want
* locked without the console sempahore held * 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 * 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) ...@@ -697,6 +698,23 @@ int __init add_preferred_console(char *name, int idx, char *options)
return 0; 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. * 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) ...@@ -708,6 +726,10 @@ int __init add_preferred_console(char *name, int idx, char *options)
void acquire_console_sem(void) void acquire_console_sem(void)
{ {
BUG_ON(in_interrupt()); BUG_ON(in_interrupt());
if (console_suspended) {
down(&secondary_console_sem);
return;
}
down(&console_sem); down(&console_sem);
console_locked = 1; console_locked = 1;
console_may_schedule = 1; console_may_schedule = 1;
...@@ -750,6 +772,10 @@ void release_console_sem(void) ...@@ -750,6 +772,10 @@ void release_console_sem(void)
unsigned long _con_start, _log_end; unsigned long _con_start, _log_end;
unsigned long wake_klogd = 0; unsigned long wake_klogd = 0;
if (console_suspended) {
up(&secondary_console_sem);
return;
}
for ( ; ; ) { for ( ; ; ) {
spin_lock_irqsave(&logbuf_lock, flags); spin_lock_irqsave(&logbuf_lock, flags);
wake_klogd |= log_start - log_end; wake_klogd |= log_start - log_end;
......
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