[PATCH v2] console: Replace #if 1 with a bool to ignore

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

There's been discussion on the fb list about the addition of
WARN_CONSOLE_UNLOCKED() inside the fb code. The complaint is that when
the fb module is loaded with lockless_register_fb the console lock is
not taken for debugging reasons. With the addition of
WARN_CONSOLE_UNLOCK() within the fb code, this causes the console to
fill up with warnings when trying to debug the fb driver.

There's also a #if 1 that enables the warning which was added before
git history, and we look down on constant #if's in the kernel nowadays
anyway.

Remove the #if 1 and add a ignore_console_lock_warning boolean that can
be set by drivers to ignore the warning in order to do debugging.

Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Reviewed-by: Hans de Goede <redacted>
Acked-by: Sergey Senozhatsky <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
Changes since V1:
 - Added comment to describe ignore_console_unlock_waring variable
 - Abide by 80 character limit

Index: linux-trace.git/include/linux/console.h
=================================--- linux-trace.git.orig/include/linux/console.h

+++ linux-trace.git/include/linux/console.h

@@ -200,11 +200,14 @@ 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(!ignore_console_lock_warning &&				\
+		!is_console_locked() && !oops_in_progress)
+/*
+ * Set ignore_console_lock_warning to true if you need to quiet
+ * WARN_CONSOLE_UNLOCKED() for debugging purposes.
+ */
+extern bool ignore_console_lock_warning;
 
 /* VESA Blanking Levels */
 #define VESA_NO_BLANKING        0

Index: linux-trace.git/kernel/printk/printk.c
=================================--- linux-trace.git.orig/kernel/printk/printk.c

+++ linux-trace.git/kernel/printk/printk.c

@@ -66,6 +66,9 @@ int console_printk[4] = {
 	CONSOLE_LOGLEVEL_DEFAULT,	/* default_console_loglevel */
 };
 
+bool ignore_console_lock_warning __read_mostly;
+EXPORT_SYMBOL(ignore_console_lock_warning);
+
 /*
  * Low level drivers may need that to know if they can schedule in
  * their unblank() callback or not. So let's export it.

On Thu, 12 Jul 2018 09:29:38 -0400
Steven Rostedt [off-list ref] wrote:

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

There's been discussion on the fb list about the addition of
WARN_CONSOLE_UNLOCKED() inside the fb code. The complaint is that when
the fb module is loaded with lockless_register_fb the console lock is
not taken for debugging reasons. With the addition of
WARN_CONSOLE_UNLOCK() within the fb code, this causes the console to
fill up with warnings when trying to debug the fb driver.

There's also a #if 1 that enables the warning which was added before
git history, and we look down on constant #if's in the kernel nowadays
anyway.

Remove the #if 1 and add a ignore_console_lock_warning boolean that can
be set by drivers to ignore the warning in order to do debugging.

Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Reviewed-by: Hans de Goede <redacted>
Acked-by: Sergey Senozhatsky <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Petr,

If you want this to go by way of fbdev tree, then can you Ack it?

-- Steve

On Thu 2018-07-12 09:30:49, Steven Rostedt wrote:

On Thu, 12 Jul 2018 09:29:38 -0400
Steven Rostedt [off-list ref] wrote:

quoted

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

There's been discussion on the fb list about the addition of
WARN_CONSOLE_UNLOCKED() inside the fb code. The complaint is that when
the fb module is loaded with lockless_register_fb the console lock is
not taken for debugging reasons. With the addition of
WARN_CONSOLE_UNLOCK() within the fb code, this causes the console to
fill up with warnings when trying to debug the fb driver.

There's also a #if 1 that enables the warning which was added before
git history, and we look down on constant #if's in the kernel nowadays
anyway.

Remove the #if 1 and add a ignore_console_lock_warning boolean that can
be set by drivers to ignore the warning in order to do debugging.

Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Reviewed-by: Hans de Goede <redacted>
Acked-by: Sergey Senozhatsky <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Petr,

If you want this to go by way of fbdev tree, then can you Ack it?

Sure.

Acked-by: Petr Mladek <pmladek@suse.com>

I assume that it will go via fbdev tree with the other changes
unless I hear otherwise.

Best Regards,
Petr

Am 12.07.2018 um 15:29 schrieb Steven Rostedt:

This resolves the problem for me.

Tested-by: Thomas Zimmermann <tzimmermann@suse.de>

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nürnberg
Tel: +49-911-74053-0; Fax: +49-911-7417755;  https://www.suse.com/
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
Graham Norton, HRB 21284 (AG Nürnberg)

On Thursday, July 12, 2018 09:29:38 AM Steven Rostedt wrote:

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

There's been discussion on the fb list about the addition of
WARN_CONSOLE_UNLOCKED() inside the fb code. The complaint is that when
the fb module is loaded with lockless_register_fb the console lock is
not taken for debugging reasons. With the addition of
WARN_CONSOLE_UNLOCK() within the fb code, this causes the console to
fill up with warnings when trying to debug the fb driver.

There's also a #if 1 that enables the warning which was added before
git history, and we look down on constant #if's in the kernel nowadays
anyway.

Remove the #if 1 and add a ignore_console_lock_warning boolean that can
be set by drivers to ignore the warning in order to do debugging.

Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Reviewed-by: Hans de Goede <redacted>
Acked-by: Sergey Senozhatsky <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Patch queued for 4.19, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

On Tuesday, July 24, 2018 06:13:19 PM Bartlomiej Zolnierkiewicz wrote:

On Thursday, July 12, 2018 09:29:38 AM Steven Rostedt wrote:

quoted

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

There's been discussion on the fb list about the addition of
WARN_CONSOLE_UNLOCKED() inside the fb code. The complaint is that when
the fb module is loaded with lockless_register_fb the console lock is
not taken for debugging reasons. With the addition of
WARN_CONSOLE_UNLOCK() within the fb code, this causes the console to
fill up with warnings when trying to debug the fb driver.

There's also a #if 1 that enables the warning which was added before
git history, and we look down on constant #if's in the kernel nowadays
anyway.

Remove the #if 1 and add a ignore_console_lock_warning boolean that can
be set by drivers to ignore the warning in order to do debugging.

Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de
Reviewed-by: Hans de Goede <redacted>
Acked-by: Sergey Senozhatsky <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Patch queued for 4.19, thanks.

Dequeued, I've just noticed a newer patch from Thomas for this issue
(I plan to apply it later this week).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics