[RFC][PATCH] vt: TIOCL to read kmsg_redirect from user space

[RFC][PATCH] vt: TIOCL to read kmsg_redirect from user space

[Rafael J. Wysocki]

Hi,

The userland suspend tool we're working on needs to get the current value
of kmsg_redirect from the kernel so that it can save it and restore it after
resume.  Unfortunetely there only is TIOCL_SETKMSGREDIRECT allowing us to
set this value from the user space.

The appended patch adds the "missing" TIOCL_GETKMSGREDIRECT that we need.

Comments welcome.

Greetings,
Rafael

---
 drivers/char/vt.c     |    4 ++++
 include/linux/tiocl.h |    1 +
 2 files changed, 5 insertions(+)

Index: linux-2.6.16-mm1/drivers/char/vt.c
===================================================================
--- linux-2.6.16-mm1.orig/drivers/char/vt.c
+++ linux-2.6.16-mm1/drivers/char/vt.c
@@ -2328,6 +2328,10 @@ int tioclinux(struct tty_struct *tty, un
 		case TIOCL_SETVESABLANK:
 			set_vesa_blanking(p);
 			break;
+		case TIOCL_GETKMSGREDIRECT:
+			data = kmsg_redirect;
+			ret = __put_user(data, p);
+			break;
 		case TIOCL_SETKMSGREDIRECT:
 			if (!capable(CAP_SYS_ADMIN)) {
 				ret = -EPERM;
Index: linux-2.6.16-mm1/include/linux/tiocl.h
===================================================================
--- linux-2.6.16-mm1.orig/include/linux/tiocl.h
+++ linux-2.6.16-mm1/include/linux/tiocl.h
@@ -34,5 +34,6 @@ struct tiocl_selection {
 #define TIOCL_SCROLLCONSOLE	13	/* scroll console */
 #define TIOCL_BLANKSCREEN	14	/* keep screen blank even if a key is pressed */
 #define TIOCL_BLANKEDSCREEN	15	/* return which vt was blanked */
+#define TIOCL_GETKMSGREDIRECT	17	/* get the vt the kernel messages are restricted to */
 
 #endif /* _LINUX_TIOCL_H */

Re: [RFC][PATCH] vt: TIOCL to read kmsg_redirect from user space

[Pavel Machek]

Hi!

> The userland suspend tool we're working on needs to get the current value
> of kmsg_redirect from the kernel so that it can save it and restore it after
> resume.  Unfortunetely there only is TIOCL_SETKMSGREDIRECT allowing us to
> set this value from the user space.
> 
> The appended patch adds the "missing" TIOCL_GETKMSGREDIRECT that we
> need.

> Comments welcome.

Looks good to me.
								Pavel

>  drivers/char/vt.c     |    4 ++++
>  include/linux/tiocl.h |    1 +
>  2 files changed, 5 insertions(+)
> 
> Index: linux-2.6.16-mm1/drivers/char/vt.c
> ===================================================================
> --- linux-2.6.16-mm1.orig/drivers/char/vt.c
> +++ linux-2.6.16-mm1/drivers/char/vt.c
> @@ -2328,6 +2328,10 @@ int tioclinux(struct tty_struct *tty, un
>  		case TIOCL_SETVESABLANK:
>  			set_vesa_blanking(p);
>  			break;
> +		case TIOCL_GETKMSGREDIRECT:
> +			data = kmsg_redirect;
> +			ret = __put_user(data, p);
> +			break;
>  		case TIOCL_SETKMSGREDIRECT:
>  			if (!capable(CAP_SYS_ADMIN)) {
>  				ret = -EPERM;
> Index: linux-2.6.16-mm1/include/linux/tiocl.h
> ===================================================================
> --- linux-2.6.16-mm1.orig/include/linux/tiocl.h
> +++ linux-2.6.16-mm1/include/linux/tiocl.h
> @@ -34,5 +34,6 @@ struct tiocl_selection {
>  #define TIOCL_SCROLLCONSOLE	13	/* scroll console */
>  #define TIOCL_BLANKSCREEN	14	/* keep screen blank even if a key is pressed */
>  #define TIOCL_BLANKEDSCREEN	15	/* return which vt was blanked */
> +#define TIOCL_GETKMSGREDIRECT	17	/* get the vt the kernel messages are restricted to */
>  
>  #endif /* _LINUX_TIOCL_H */

-- 
Picture of sleeping (Linux) penguin wanted...