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authorLinus Torvalds <torvalds@g5.osdl.org>2006-06-19 18:16:01 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-19 18:16:01 -0700
commit557240b48e2dc4f6fa878afc3fc767ad745ca7ed (patch)
tree354e9de17c28b438db675f6a2b779415f1634c45 /kernel/printk.c
parentMake sure to re-enable SCI after an ACPI suspend (diff)
downloadlinux-dev-557240b48e2dc4f6fa878afc3fc767ad745ca7ed.tar.xz
linux-dev-557240b48e2dc4f6fa878afc3fc767ad745ca7ed.zip
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>
Diffstat (limited to '')
-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);
* 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
@@ -698,6 +699,23 @@ int __init add_preferred_console(char *name, int idx, char *options)
}
/**
+ * 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.
*
* Acquires a semaphore which guarantees that the caller has
@@ -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;