| Message ID | 20180719101601.25076-2-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu 2018-07-19 12:16:00, Thomas Zimmermann wrote: > 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: Petr Mladek <pmladek@suse.com> I have vacation the following two weeks. I prefer this version over the previous one but I could live with both. Best Regards, Petr
On Thursday, July 19, 2018 12:16:00 PM Thomas Zimmermann wrote: > 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> Patch queued for 4.19 (w/ <asm/atomic.h> -> <linux/atomic.h> fixup), thanks. Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics
On Thu, 19 Jul 2018 12:16:00 +0200 Thomas Zimmermann <tzimmermann@suse.de> wrote: > 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. You can also add a reference to that patch as well: Link: http://lkml.kernel.org/r/20180712092938.22e33641@gandalf.local.home -- Steve > > Link: http://lkml.kernel.org/r/717e6337-e7a6-7a92-1c1b-8929a25696b5@suse.de > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > --- > include/linux/console.h | 14 +++++++++----- > kernel/printk/printk.c | 3 +++ > 2 files changed, 12 insertions(+), 5 deletions(-) > > diff --git a/include/linux/console.h b/include/linux/console.h > index f59f3dbca65c..a3307bcab947 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 <asm/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 > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index 3f041e7cbfc9..7d32a86758cd 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -66,6 +66,9 @@ int console_printk[4] = { > CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ > }; > > +atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); > +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.
diff --git a/include/linux/console.h b/include/linux/console.h index f59f3dbca65c..a3307bcab947 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 <asm/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 diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 3f041e7cbfc9..7d32a86758cd 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -66,6 +66,9 @@ int console_printk[4] = { CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */ }; +atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0); +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.
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> --- include/linux/console.h | 14 +++++++++----- kernel/printk/printk.c | 3 +++ 2 files changed, 12 insertions(+), 5 deletions(-)