X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fkernel_lock.c;h=01a3c22c1b5a9c951dc33a0c37179306f36e18e4;hb=ea2ac5a3b7d33ff9f41ddcee2a92c95b5a32f4e2;hp=cb5490ec00f20f4fea3640275192f20d942a7fba;hpb=fac84ef26759a3725bfc53ae3abf21976360aff3;p=linux-2.6-omap-h63xx.git

diff --git a/lib/kernel_lock.c b/lib/kernel_lock.c
index cb5490ec00f..01a3c22c1b5 100644
--- a/lib/kernel_lock.c
+++ b/lib/kernel_lock.c
@@ -2,97 +2,19 @@
  * lib/kernel_lock.c
  *
  * This is the traditional BKL - big kernel lock. Largely
- * relegated to obsolescense, but used by various less
+ * relegated to obsolescence, but used by various less
  * important (or lazy) subsystems.
  */
 #include <linux/smp_lock.h>
 #include <linux/module.h>
 #include <linux/kallsyms.h>
-
-#ifdef CONFIG_PREEMPT_BKL
-/*
- * The 'big kernel semaphore'
- *
- * This mutex is taken and released recursively by lock_kernel()
- * and unlock_kernel().  It is transparently dropped and reaquired
- * over schedule().  It is used to protect legacy code that hasn't
- * been migrated to a proper locking design yet.
- *
- * Note: code locked by this semaphore will only be serialized against
- * other code using the same locking facility. The code guarantees that
- * the task remains on the same CPU.
- *
- * Don't use in new code.
- */
-static DECLARE_MUTEX(kernel_sem);
-
-/*
- * Re-acquire the kernel semaphore.
- *
- * This function is called with preemption off.
- *
- * We are executing in schedule() so the code must be extremely careful
- * about recursion, both due to the down() and due to the enabling of
- * preemption. schedule() will re-check the preemption flag after
- * reacquiring the semaphore.
- */
-int __lockfunc __reacquire_kernel_lock(void)
-{
-	struct task_struct *task = current;
-	int saved_lock_depth = task->lock_depth;
-
-	BUG_ON(saved_lock_depth < 0);
-
-	task->lock_depth = -1;
-	preempt_enable_no_resched();
-
-	down(&kernel_sem);
-
-	preempt_disable();
-	task->lock_depth = saved_lock_depth;
-
-	return 0;
-}
-
-void __lockfunc __release_kernel_lock(void)
-{
-	up(&kernel_sem);
-}
-
-/*
- * Getting the big kernel semaphore.
- */
-void __lockfunc lock_kernel(void)
-{
-	struct task_struct *task = current;
-	int depth = task->lock_depth + 1;
-
-	if (likely(!depth))
-		/*
-		 * No recursion worries - we set up lock_depth _after_
-		 */
-		down(&kernel_sem);
-
-	task->lock_depth = depth;
-}
-
-void __lockfunc unlock_kernel(void)
-{
-	struct task_struct *task = current;
-
-	BUG_ON(task->lock_depth < 0);
-
-	if (likely(--task->lock_depth < 0))
-		up(&kernel_sem);
-}
-
-#else
+#include <linux/semaphore.h>
 
 /*
  * The 'big kernel lock'
  *
  * This spinlock is taken and released recursively by lock_kernel()
- * and unlock_kernel().  It is transparently dropped and reaquired
+ * and unlock_kernel().  It is transparently dropped and reacquired
  * over schedule().  It is used to protect legacy code that hasn't
  * been migrated to a proper locking design yet.
  *
@@ -132,7 +54,7 @@ void __lockfunc __release_kernel_lock(void)
 }
 
 /*
- * These are the BKL spinlocks - we try to be polite about preemption. 
+ * These are the BKL spinlocks - we try to be polite about preemption.
  * If SMP is not on (ie UP preemption), this all goes away because the
  * _raw_spin_trylock() will always succeed.
  */
@@ -177,7 +99,12 @@ static inline void __lock_kernel(void)
 
 static inline void __unlock_kernel(void)
 {
-	spin_unlock(&kernel_flag);
+	/*
+	 * the BKL is not covered by lockdep, so we open-code the
+	 * unlocking sequence (and thus avoid the dep-chain ops):
+	 */
+	_raw_spin_unlock(&kernel_flag);
+	preempt_enable();
 }
 
 /*
@@ -201,8 +128,6 @@ void __lockfunc unlock_kernel(void)
 		__unlock_kernel();
 }
 
-#endif
-
 EXPORT_SYMBOL(lock_kernel);
 EXPORT_SYMBOL(unlock_kernel);