diff options
| author | Thomas Zimmermann <tzimmermann@suse.de> | 2018-07-31 13:06:57 +0200 |
|---|---|---|
| committer | Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> | 2018-07-31 13:06:57 +0200 |
| commit | 56e6c104e4f151e19eb410004405ec52b4f8605a (patch) | |
| tree | ae7567c188e3306e7cc02bcd6db5f9025edef48b /include | |
| parent | cb782a3fa952478177341e67275885ae52340f99 (diff) | |
console: Replace #if 0 with atomic var 'ignore_console_lock_warning'
The macro WARN_CONSOLE_UNLOCKED prints a warning when a thread enters
the console's critical section without having acquired the console
lock. The console lock can be ignored when debugging the console using
printk, but this makes WARN_CONSOLE_UNLOCKED generate unnecessary
warnings.
The variable ignore_console_lock_warning temporarily disables
WARN_CONSOLE_UNLOCKED. Developers interested in debugging the console's
critical sections should increment it before entering the CS and
decrement it after leaving the CS. Setting ignore_console_lock_warning
is only for debugging. Regular operation should not manipulate it.
Acknoledgements: This patch is based on an earlier version by Steven
Rostedt. The use of atomic increment/decrement was suggested by Petr
Mladek.
Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
[b.zolnierkie: use <linux/atomic.h>]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/console.h | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index f59f3dbca65c..ec9bdb3d7bab 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -14,6 +14,7 @@ #ifndef _LINUX_CONSOLE_H_ #define _LINUX_CONSOLE_H_ 1 +#include <linux/atomic.h> #include <linux/types.h> struct vc_data; @@ -201,11 +202,14 @@ void vcs_make_sysfs(int index); void vcs_remove_sysfs(int index); /* 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) -#else -#define WARN_CONSOLE_UNLOCKED() -#endif +#define WARN_CONSOLE_UNLOCKED() \ + WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ + !is_console_locked() && !oops_in_progress) +/* + * Increment ignore_console_lock_warning if you need to quiet + * WARN_CONSOLE_UNLOCKED() for debugging purposes. + */ +extern atomic_t ignore_console_lock_warning; /* VESA Blanking Levels */ #define VESA_NO_BLANKING 0 |