[PATCH 04/33] vt: More locking checks

Daniel Vetter
2019-05-28T09:03:18Z

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>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.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(-)

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

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