From: "Rafael J. Wysocki" Change suspend_console() so that it waits for all consoles to flush the remaining messages and make it possible to switch the console suspending off with the help of a Kconfig option. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Signed-off-by: Andrew Morton --- include/linux/console.h | 5 +++++ kernel/power/Kconfig | 11 +++++++++++ kernel/printk.c | 8 ++++++++ 3 files changed, 24 insertions(+) diff -puN include/linux/console.h~pm-make-it-possible-to-disable-console-suspending include/linux/console.h --- a/include/linux/console.h~pm-make-it-possible-to-disable-console-suspending +++ a/include/linux/console.h @@ -120,9 +120,14 @@ extern void console_stop(struct console extern void console_start(struct console *); extern int is_console_locked(void); +#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND /* Suspend and resume console messages over PM events */ extern void suspend_console(void); extern void resume_console(void); +#else +static inline void suspend_console(void) {} +static inline void resume_console(void) {} +#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */ /* Some debug stub to catch some of the obvious races in the VT code */ #if 1 diff -puN kernel/power/Kconfig~pm-make-it-possible-to-disable-console-suspending kernel/power/Kconfig --- a/kernel/power/Kconfig~pm-make-it-possible-to-disable-console-suspending +++ a/kernel/power/Kconfig @@ -36,6 +36,17 @@ config PM_DEBUG code. This is helpful when debugging and reporting various PM bugs, like suspend support. +config PM_DISABLE_CONSOLE_SUSPEND + bool "Keep console(s) enabled during suspend/resume (DANGEROUS)" + depends on PM && PM_DEBUG + default n + ---help--- + This option turns off the console suspend mechanism that prevents + debug messages from reaching the console during the suspend/resume + operations. This may be helpful when debugging device drivers' + suspend/resume routines, but may itself lead to problems, for example + if netconsole is used. + config PM_TRACE bool "Suspend/resume event tracing" depends on PM && PM_DEBUG && X86_32 && EXPERIMENTAL diff -puN kernel/printk.c~pm-make-it-possible-to-disable-console-suspending kernel/printk.c --- a/kernel/printk.c~pm-make-it-possible-to-disable-console-suspending +++ a/kernel/printk.c @@ -721,6 +721,7 @@ int __init add_preferred_console(char *n return 0; } +#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND /** * suspend_console - suspend the console subsystem * @@ -728,8 +729,14 @@ int __init add_preferred_console(char *n */ void suspend_console(void) { + printk("Suspending console(s)\n"); acquire_console_sem(); console_suspended = 1; + /* This is needed so that all of the messages that have already been + * written to all consoles can be actually transmitted (eg. over a + * network) before we try to suspend the consoles' devices. + */ + ssleep(2); } void resume_console(void) @@ -737,6 +744,7 @@ void resume_console(void) console_suspended = 0; release_console_sem(); } +#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */ /** * acquire_console_sem - lock the console system for exclusive use. _