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vt: More locking checks 

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528090304.9388-5-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2019-05-28 11:02:35 +02:00
parent a135513c0b
commit ddde3c18b7
2 changed files with 17 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/tty/vt/vt.c
View File

@ -3822,6 +3822,8 @@ 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;
@ -3833,6 +3835,20 @@ 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

5
include/linux/console_struct.h
View File

@ -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 */