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author | Bernhard Walle <bernhard@bwalle.de> | 2009-12-15 03:00:43 +0100 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 17:53:28 +0100 |
commit | 5ada918b82399eef3afd6a71e3637697d6bd719f (patch) | |
tree | 9bff5251d9d21960726078c2117a0ab19ca25956 /drivers/char | |
parent | cs5535: drop the Geode-specific MFGPT/GPIO code (diff) | |
download | linux-5ada918b82399eef3afd6a71e3637697d6bd719f.tar.xz linux-5ada918b82399eef3afd6a71e3637697d6bd719f.zip |
vt: introduce and use vt_kmsg_redirect() function
The kernel offers with TIOCL_GETKMSGREDIRECT ioctl() the possibility to
redirect the kernel messages to a specific console.
However, since it's not possible to switch to the kernel message console
after a panic(), it would be nice if the kernel would print the panic
message on the current console.
This patch series adds a new interface to access the global kmsg_redirect
variable by a function to be able to use it in code where
CONFIG_VT_CONSOLE is not set (kernel/panic.c).
This patch:
Instead of using and exporting a global value kmsg_redirect, introduce a
function vt_kmsg_redirect() that both can set and return the console where
messages are printed.
Change all users of kmsg_redirect (the VT code itself and kernel/power.c)
to the new interface.
The main advantage is that vt_kmsg_redirect() can also be used when
CONFIG_VT_CONSOLE is not set.
Signed-off-by: Bernhard Walle <bernhard@bwalle.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r-- | drivers/char/vt.c | 43 |
1 files changed, 37 insertions, 6 deletions
diff --git a/drivers/char/vt.c b/drivers/char/vt.c index 1e3d728dbf7e..e43fbc66aef0 100644 --- a/drivers/char/vt.c +++ b/drivers/char/vt.c @@ -184,12 +184,10 @@ static DECLARE_WORK(console_work, console_callback); * fg_console is the current virtual console, * last_console is the last used one, * want_console is the console we want to switch to, - * kmsg_redirect is the console for kernel messages, */ int fg_console; int last_console; int want_console = -1; -int kmsg_redirect; /* * For each existing display, we have a pointer to console currently visible @@ -2434,6 +2432,37 @@ struct tty_driver *console_driver; #ifdef CONFIG_VT_CONSOLE +/** + * vt_kmsg_redirect() - Sets/gets the kernel message console + * @new: The new virtual terminal number or -1 if the console should stay + * unchanged + * + * By default, the kernel messages are always printed on the current virtual + * console. However, the user may modify that default with the + * TIOCL_SETKMSGREDIRECT ioctl call. + * + * This function sets the kernel message console to be @new. It returns the old + * virtual console number. The virtual terminal number 0 (both as parameter and + * return value) means no redirection (i.e. always printed on the currently + * active console). + * + * The parameter -1 means that only the current console is returned, but the + * value is not modified. You may use the macro vt_get_kmsg_redirect() in that + * case to make the code more understandable. + * + * When the kernel is compiled without CONFIG_VT_CONSOLE, this function ignores + * the parameter and always returns 0. + */ +int vt_kmsg_redirect(int new) +{ + static int kmsg_con; + + if (new != -1) + return xchg(&kmsg_con, new); + else + return kmsg_con; +} + /* * Console on virtual terminal * @@ -2448,6 +2477,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) const ushort *start; ushort cnt = 0; ushort myx; + int kmsg_console; /* console busy or not yet initialized */ if (!printable) @@ -2455,8 +2485,9 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) if (!spin_trylock(&printing_lock)) return; - if (kmsg_redirect && vc_cons_allocated(kmsg_redirect - 1)) - vc = vc_cons[kmsg_redirect - 1].d; + kmsg_console = vt_get_kmsg_redirect(); + if (kmsg_console && vc_cons_allocated(kmsg_console - 1)) + vc = vc_cons[kmsg_console - 1].d; /* read `x' only after setting currcons properly (otherwise the `x' macro will read the x of the foreground console). */ @@ -2613,7 +2644,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg) ret = set_vesa_blanking(p); break; case TIOCL_GETKMSGREDIRECT: - data = kmsg_redirect; + data = vt_get_kmsg_redirect(); ret = __put_user(data, p); break; case TIOCL_SETKMSGREDIRECT: @@ -2623,7 +2654,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg) if (get_user(data, p+1)) ret = -EFAULT; else - kmsg_redirect = data; + vt_kmsg_redirect(data); } break; case TIOCL_GETFGCONSOLE: |