vt: More locking checks (ddde3c18) · Commits · 戴 / test

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

drivers/tty/vt/vt.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -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

include/linux/console_struct.h

+1 −4

Original line number	Diff line number	Diff line
		@@ -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 */

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