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-rw-r--r--kernel/printk.c28
1 files changed, 27 insertions, 1 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index c056f3324432..19a955619294 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -67,6 +67,7 @@ EXPORT_SYMBOL(oops_in_progress);
67 * driver system. 67 * driver system.
68 */ 68 */
69static DECLARE_MUTEX(console_sem); 69static DECLARE_MUTEX(console_sem);
70static DECLARE_MUTEX(secondary_console_sem);
70struct console *console_drivers; 71struct console *console_drivers;
71/* 72/*
72 * This is used for debugging the mess that is the VT code by 73 * This is used for debugging the mess that is the VT code by
@@ -76,7 +77,7 @@ struct console *console_drivers;
76 * path in the console code where we end up in places I want 77 * path in the console code where we end up in places I want
77 * locked without the console sempahore held 78 * locked without the console sempahore held
78 */ 79 */
79static int console_locked; 80static int console_locked, console_suspended;
80 81
81/* 82/*
82 * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars 83 * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars
@@ -698,6 +699,23 @@ int __init add_preferred_console(char *name, int idx, char *options)
698} 699}
699 700
700/** 701/**
702 * suspend_console - suspend the console subsystem
703 *
704 * This disables printk() while we go into suspend states
705 */
706void suspend_console(void)
707{
708 acquire_console_sem();
709 console_suspended = 1;
710}
711
712void resume_console(void)
713{
714 console_suspended = 0;
715 release_console_sem();
716}
717
718/**
701 * acquire_console_sem - lock the console system for exclusive use. 719 * acquire_console_sem - lock the console system for exclusive use.
702 * 720 *
703 * Acquires a semaphore which guarantees that the caller has 721 * Acquires a semaphore which guarantees that the caller has
@@ -708,6 +726,10 @@ int __init add_preferred_console(char *name, int idx, char *options)
708void acquire_console_sem(void) 726void acquire_console_sem(void)
709{ 727{
710 BUG_ON(in_interrupt()); 728 BUG_ON(in_interrupt());
729 if (console_suspended) {
730 down(&secondary_console_sem);
731 return;
732 }
711 down(&console_sem); 733 down(&console_sem);
712 console_locked = 1; 734 console_locked = 1;
713 console_may_schedule = 1; 735 console_may_schedule = 1;
@@ -750,6 +772,10 @@ void release_console_sem(void)
750 unsigned long _con_start, _log_end; 772 unsigned long _con_start, _log_end;
751 unsigned long wake_klogd = 0; 773 unsigned long wake_klogd = 0;
752 774
775 if (console_suspended) {
776 up(&secondary_console_sem);
777 return;
778 }
753 for ( ; ; ) { 779 for ( ; ; ) {
754 spin_lock_irqsave(&logbuf_lock, flags); 780 spin_lock_irqsave(&logbuf_lock, flags);
755 wake_klogd |= log_start - log_end; 781 wake_klogd |= log_start - log_end;