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

Steven Rostedt
2018-07-12T13:30:55Z

On Thu, 12 Jul 2018 09:29:38 -0400
Steven Rostedt <rostedt@goodmis.org> 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 <hdegoede@redhat.com>
> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> 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

> ---
> 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.