vt,console,kdb: implement atomic console enter/leave functions

[deliverable/linux.git] / drivers / char / vt.c

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 7cdb6ee569cd7ca592bedfea458f0b676ec937af..117ce99115dc1cfe8e36d7e16768738de9625dbd 100644 (file)
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -187,10 +187,15 @@ 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,
+ * saved_* variants are for save/restore around kernel debugger enter/leave
  */
 int fg_console;
 int last_console;
 int want_console = -1;
+int saved_fg_console;
+int saved_last_console;
+int saved_want_console;
+int saved_vc_mode;
 
 /*
  * For each existing display, we have a pointer to console currently visible
@@ -3413,6 +3418,62 @@ int con_is_bound(const struct consw *csw)
 }
 EXPORT_SYMBOL(con_is_bound);
 
+/**
+ * con_debug_enter - prepare the console for the kernel debugger
+ * @sw: console driver
+ *
+ * Called when the console is taken over by the kernel debugger, this
+ * function needs to save the current console state, then put the console
+ * into a state suitable for the kernel debugger.
+ *
+ * RETURNS:
+ * Zero on success, nonzero if a failure occurred when trying to prepare
+ * the console for the debugger.
+ */
+int con_debug_enter(struct vc_data *vc)
+{
+       int ret = 0;
+
+       saved_fg_console = fg_console;
+       saved_last_console = last_console;
+       saved_want_console = want_console;
+       saved_vc_mode = vc->vc_mode;
+       vc->vc_mode = KD_TEXT;
+       console_blanked = 0;
+       if (vc->vc_sw->con_debug_enter)
+               ret = vc->vc_sw->con_debug_enter(vc);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(con_debug_enter);
+
+/**
+ * con_debug_leave - restore console state
+ * @sw: console driver
+ *
+ * Restore the console state to what it was before the kernel debugger
+ * was invoked.
+ *
+ * RETURNS:
+ * Zero on success, nonzero if a failure occurred when trying to restore
+ * the console.
+ */
+int con_debug_leave(void)
+{
+       struct vc_data *vc;
+       int ret = 0;
+
+       fg_console = saved_fg_console;
+       last_console = saved_last_console;
+       want_console = saved_want_console;
+       vc_cons[fg_console].d->vc_mode = saved_vc_mode;
+
+       vc = vc_cons[fg_console].d;
+       if (vc->vc_sw->con_debug_leave)
+               ret = vc->vc_sw->con_debug_leave(vc);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(con_debug_leave);
+
 /**
  * register_con_driver - register console driver to console layer
  * @csw: console driver