VT locking patch #2

@@ -24,6 +24,7 @@
 #include <linux/consolemap.h>
 #include <linux/selection.h>
 #include <linux/tiocl.h>
+#include <linux/console.h>
 
 #ifndef MIN
 #define MIN(a,b)	((a) < (b) ? (a) : (b))

@@ -290,7 +291,10 @@
 	int	pasted = 0, count;
 	DECLARE_WAITQUEUE(wait, current);
 
+	acquire_console_sem();
 	poke_blanked_console();
+	release_console_sem();
+
 	add_wait_queue(&vt->paste_wait, &wait);
 	while (sel_buffer && sel_buffer_lth > pasted) {
 		set_current_state(TASK_INTERRUPTIBLE);

@@ -1484,7 +1484,12 @@
 #ifdef CONFIG_VT
 	if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
 		unsigned int currcons = tty->index;
-		if (vc_resize(currcons, tmp_ws.ws_col, tmp_ws.ws_row))
+		int rc;
+
+		acquire_console_sem();	       
+		rc = vc_resize(currcons, tmp_ws.ws_col, tmp_ws.ws_row);
+		release_console_sem();
+		if (rc)
 			return -ENXIO;
 	}
 #endif

380 lines not on this page · raw message

139 lines not on this page · raw message

@@ -102,6 +102,14 @@
 extern void release_console_sem(void);
 extern void console_conditional_schedule(void);
 extern void console_unblank(void);
+extern int is_console_locked(void);
+
+/* Some debug stub to catch some of the obvious races in the VT code */
+#if 1
+#define WARN_CONSOLE_UNLOCKED()	WARN_ON(!is_console_locked() && !oops_in_progress)
+#else
+#define WARN_CONSOLE_UNLOCKED()
+#endif
 
 /* VESA Blanking Levels */
 #define VESA_NO_BLANKING        0

@@ -62,6 +62,15 @@
  */
 static DECLARE_MUTEX(console_sem);
 struct console *console_drivers;
+/*
+ * This is used for debugging the mess that is the VT code by
+ * keeping track if we have the console semaphore held. It's
+ * definitely not the perfect debug tool (we don't know if _WE_
+ * hold it are racing, but it helps tracking those weird code
+ * path in the console code where we end up in places I want
+ * locked without the console sempahore held
+ */
+static int console_locked;
 
 /*
  * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars

@@ -524,6 +533,7 @@
 		goto out;
 	}
 	if (!down_trylock(&console_sem)) {
+		console_locked = 1;
 		/*
 		 * We own the drivers.  We can drop the spinlock and let
 		 * release_console_sem() print the text

@@ -557,10 +567,17 @@
 	if (in_interrupt())
 		BUG();
 	down(&console_sem);
+	console_locked = 1;
 	console_may_schedule = 1;
 }
 EXPORT_SYMBOL(acquire_console_sem);
 
+int is_console_locked(void)
+{
+	return console_locked;
+}
+EXPORT_SYMBOL(is_console_locked);
+
 /**
  * release_console_sem - unlock the console system
  *

@@ -592,12 +609,14 @@
 		spin_unlock_irqrestore(&logbuf_lock, flags);
 		call_console_drivers(_con_start, _log_end);
 	}
+	console_locked = 0;
 	console_may_schedule = 0;
 	up(&console_sem);
 	spin_unlock_irqrestore(&logbuf_lock, flags);
 	if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
 		wake_up_interruptible(&log_wait);
 }
+EXPORT_SYMBOL(release_console_sem);
 
 /** console_conditional_schedule - yield the CPU if required
  *

@@ -633,6 +652,7 @@
 	 */
 	if (down_trylock(&console_sem) != 0)
 		return;
+	console_locked = 1;
 	console_may_schedule = 0;
 	for (c = console_drivers; c != NULL; c = c->next)
 		if ((c->flags & CON_ENABLED) && c->unblank)

@@ -6,6 +6,7 @@
 
 #include <linux/vt_kern.h>
 #include <linux/kbd_kern.h>
+#include <linux/console.h>
 #include "power.h"
 
 static int new_loglevel = 10;

@@ -18,14 +19,20 @@
 	console_loglevel = new_loglevel;
 
 #ifdef SUSPEND_CONSOLE
+	acquire_console_sem();
+
 	orig_fgconsole = fg_console;
 
-	if (vc_allocate(SUSPEND_CONSOLE))
+	if (vc_allocate(SUSPEND_CONSOLE)) {
 	  /* we can't have a free VC for now. Too bad,
 	   * we don't want to mess the screen for now. */
+		release_console_sem();
 		return 1;
+	}
 
 	set_console(SUSPEND_CONSOLE);
+	release_console_sem();
+
 	if (vt_waitactive(SUSPEND_CONSOLE)) {
 		pr_debug("Suspend: Can't switch VCs.");
 		return 1;

@@ -40,12 +47,9 @@
 {
 	console_loglevel = orig_loglevel;
 #ifdef SUSPEND_CONSOLE
+	acquire_console_sem();
 	set_console(orig_fgconsole);
-
-	/* FIXME: 
-	 * This following part is left over from swsusp. Is it really needed?
-	 */
-	update_screen(fg_console);
+	release_console_sem();
 #endif
 	return;
 }