[04/33] vt: More locking checks
diff mbox series

Message ID 20190524085354.27411-5-daniel.vetter@ffwll.ch
State New
Headers show
Series
  • fbcon notifier begone!
Related show

Commit Message

Daniel Vetter May 24, 2019, 8:53 a.m. UTC
I honestly have no idea what the subtle differences between
con_is_visible, con_is_fg (internal to vt.c) and con_is_bound are. But
it looks like both vc->vc_display_fg and con_driver_map are protected
by the console_lock, so probably better if we hold that when checking
this.

To do that I had to deinline the con_is_visible function.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Martin Hostettler <textshell@uchuujin.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mikulas Patocka <mpatocka@redhat.com>
---
 drivers/tty/vt/vt.c            | 16 ++++++++++++++++
 include/linux/console_struct.h |  5 +----
 2 files changed, 17 insertions(+), 4 deletions(-)

Comments

Daniel Vetter May 27, 2019, 7:08 a.m. UTC | #1
On Fri, May 24, 2019 at 10:53:25AM +0200, Daniel Vetter wrote:
> I honestly have no idea what the subtle differences between
> con_is_visible, con_is_fg (internal to vt.c) and con_is_bound are. But
> it looks like both vc->vc_display_fg and con_driver_map are protected
> by the console_lock, so probably better if we hold that when checking
> this.
> 
> To do that I had to deinline the con_is_visible function.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
> Cc: Martin Hostettler <textshell@uchuujin.de>
> Cc: Adam Borowski <kilobyte@angband.pl>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Mikulas Patocka <mpatocka@redhat.com>

Hi Greg,

Do you want to merge this through your console tree or ack for merging
through drm/fbdev? It's part of a bigger series, and I'd like to have more
testing with this in our trees, but also ok to merge stand-alone if you
prefer that. It's just locking checks and some docs.

Same for the preceeding patch in this series here.

Thanks, Daniel


> ---
>  drivers/tty/vt/vt.c            | 16 ++++++++++++++++
>  include/linux/console_struct.h |  5 +----
>  2 files changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index bc9813b14c58..a8988a085138 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -3815,6 +3815,8 @@ int con_is_bound(const struct consw *csw)
>  {
>  	int i, bound = 0;
>  
> +	WARN_CONSOLE_UNLOCKED();
> +
>  	for (i = 0; i < MAX_NR_CONSOLES; i++) {
>  		if (con_driver_map[i] == csw) {
>  			bound = 1;
> @@ -3826,6 +3828,20 @@ int con_is_bound(const struct consw *csw)
>  }
>  EXPORT_SYMBOL(con_is_bound);
>  
> +/**
> + * con_is_visible - checks whether the current console is visible
> + * @vc: virtual console
> + *
> + * RETURNS: zero if not visible, nonzero if visible
> + */
> +bool con_is_visible(const struct vc_data *vc)
> +{
> +	WARN_CONSOLE_UNLOCKED();
> +
> +	return *vc->vc_display_fg == vc;
> +}
> +EXPORT_SYMBOL(con_is_visible);
> +
>  /**
>   * con_debug_enter - prepare the console for the kernel debugger
>   * @sw: console driver
> diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
> index ed798e114663..24d4c16e3ae0 100644
> --- a/include/linux/console_struct.h
> +++ b/include/linux/console_struct.h
> @@ -168,9 +168,6 @@ extern void vc_SAK(struct work_struct *work);
>  
>  #define CUR_DEFAULT CUR_UNDERLINE
>  
> -static inline bool con_is_visible(const struct vc_data *vc)
> -{
> -	return *vc->vc_display_fg == vc;
> -}
> +bool con_is_visible(const struct vc_data *vc);
>  
>  #endif /* _LINUX_CONSOLE_STRUCT_H */
> -- 
> 2.20.1
>
Greg Kroah-Hartman May 27, 2019, 7:22 a.m. UTC | #2
On Mon, May 27, 2019 at 09:08:58AM +0200, Daniel Vetter wrote:
> On Fri, May 24, 2019 at 10:53:25AM +0200, Daniel Vetter wrote:
> > I honestly have no idea what the subtle differences between
> > con_is_visible, con_is_fg (internal to vt.c) and con_is_bound are. But
> > it looks like both vc->vc_display_fg and con_driver_map are protected
> > by the console_lock, so probably better if we hold that when checking
> > this.
> > 
> > To do that I had to deinline the con_is_visible function.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
> > Cc: Martin Hostettler <textshell@uchuujin.de>
> > Cc: Adam Borowski <kilobyte@angband.pl>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Mikulas Patocka <mpatocka@redhat.com>
> 
> Hi Greg,
> 
> Do you want to merge this through your console tree or ack for merging
> through drm/fbdev? It's part of a bigger series, and I'd like to have more
> testing with this in our trees, but also ok to merge stand-alone if you
> prefer that. It's just locking checks and some docs.
> 
> Same for the preceeding patch in this series here.

For all of these, please take them through your tree(s):

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Patch
diff mbox series

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index bc9813b14c58..a8988a085138 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3815,6 +3815,8 @@  int con_is_bound(const struct consw *csw)
 {
 	int i, bound = 0;
 
+	WARN_CONSOLE_UNLOCKED();
+
 	for (i = 0; i < MAX_NR_CONSOLES; i++) {
 		if (con_driver_map[i] == csw) {
 			bound = 1;
@@ -3826,6 +3828,20 @@  int con_is_bound(const struct consw *csw)
 }
 EXPORT_SYMBOL(con_is_bound);
 
+/**
+ * con_is_visible - checks whether the current console is visible
+ * @vc: virtual console
+ *
+ * RETURNS: zero if not visible, nonzero if visible
+ */
+bool con_is_visible(const struct vc_data *vc)
+{
+	WARN_CONSOLE_UNLOCKED();
+
+	return *vc->vc_display_fg == vc;
+}
+EXPORT_SYMBOL(con_is_visible);
+
 /**
  * con_debug_enter - prepare the console for the kernel debugger
  * @sw: console driver
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index ed798e114663..24d4c16e3ae0 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -168,9 +168,6 @@  extern void vc_SAK(struct work_struct *work);
 
 #define CUR_DEFAULT CUR_UNDERLINE
 
-static inline bool con_is_visible(const struct vc_data *vc)
-{
-	return *vc->vc_display_fg == vc;
-}
+bool con_is_visible(const struct vc_data *vc);
 
 #endif /* _LINUX_CONSOLE_STRUCT_H */