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authorThomas Zimmermann <tzimmermann@suse.de>2018-07-31 13:06:57 +0200
committerBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>2018-07-31 13:06:57 +0200
commit56e6c104e4f151e19eb410004405ec52b4f8605a (patch)
treeae7567c188e3306e7cc02bcd6db5f9025edef48b /include/linux
parentcb782a3fa952478177341e67275885ae52340f99 (diff)
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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/linux')
-rw-r--r--include/linux/console.h14
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