[PATCH] printk: Try to describe real console_sem dependecies using the crosslock feature

[Petr Mladek]

console_sem might be newly taken and released by different
processes. This is an attempt to check the crossrelease
dependencies.
---
 kernel/printk/printk.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 040fb948924e..bda25feae0d5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -83,9 +83,9 @@ struct console *console_drivers;
 EXPORT_SYMBOL_GPL(console_drivers);
 
 #ifdef CONFIG_LOCKDEP
-static struct lockdep_map console_lock_dep_map = {
-	.name = "console_lock"
-};
+static struct lockdep_map_cross console_lock_dep_map =
+	STATIC_CROSS_LOCKDEP_MAP_INIT("console_lock", &console_sem);
+
 static struct lockdep_map console_owner_dep_map = {
 	.name = "console_owner"
 };
@@ -218,7 +218,7 @@ static int nr_ext_console_drivers;
  */
 #define down_console_sem() do { \
 	down(&console_sem);\
-	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
+	mutex_acquire((struct lockdep_map *)&console_lock_dep_map, 0, 0, _RET_IP_);\
 } while (0)
 
 static int __down_trylock_console_sem(unsigned long ip)
@@ -237,7 +237,7 @@ static int __down_trylock_console_sem(unsigned long ip)
 
 	if (lock_failed)
 		return 1;
-	mutex_acquire(&console_lock_dep_map, 0, 1, ip);
+	mutex_acquire((struct lockdep_map *)&console_lock_dep_map, 0, 1, ip);
 	return 0;
 }
 #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
@@ -246,7 +246,7 @@ static void __up_console_sem(unsigned long ip)
 {
 	unsigned long flags;
 
-	mutex_release(&console_lock_dep_map, 1, ip);
+	mutex_release((struct lockdep_map *)&console_lock_dep_map, 1, ip);
 
 	printk_safe_enter_irqsave(flags);
 	up(&console_sem);
@@ -1797,13 +1797,6 @@ asmlinkage int vprintk_emit(int facility, int level,
 				spin_release(&console_owner_dep_map, 1, _THIS_IP_);
 				printk_safe_exit_irqrestore(flags);
 
-				/*
-				 * The owner passed the console lock to us.
-				 * Since we did not spin on console lock, annotate
-				 * this as a trylock. Otherwise lockdep will
-				 * complain.
-				 */
-				mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
 				console_unlock();
 				printk_safe_enter_irqsave(flags);
 			}
@@ -2334,10 +2327,10 @@ void console_unlock(void)
 		/* The waiter is now free to continue */
 		spin_release(&console_owner_dep_map, 1, _THIS_IP_);
 		/*
-		 * Hand off console_lock to waiter. The waiter will perform
-		 * the up(). After this, the waiter is the console_lock owner.
+		 * Hand off console_lock to waiter. After this, the waiter
+		 * is the console_lock owner.
 		 */
-		mutex_release(&console_lock_dep_map, 1, _THIS_IP_);
+		lock_commit_crosslock((struct lockdep_map *)&console_lock_dep_map);
 		printk_safe_exit_irqrestore(flags);
 		/* Note, if waiter is set, logbuf_lock is not held */
 		return;
-- 
2.13.6