sched: remove the !PREEMPT_BKL code

remove the !PREEMPT_BKL code.

this removes 160 lines of legacy code.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/hardirq.h

@@ -72,11 +72,7 @@
 #define in_softirq()		(softirq_count())
 #define in_interrupt()		(irq_count())
 
-#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
-# define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
-#else
-# define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != 0)
-#endif
+#define in_atomic()		((preempt_count() & ~PREEMPT_ACTIVE) != 0)
 
 #ifdef CONFIG_PREEMPT
 # define PREEMPT_CHECK_OFFSET 1

include/linux/smp_lock.h

@@ -17,22 +17,10 @@ extern void __lockfunc __release_kernel_lock(void);
 		__release_kernel_lock();	\
 } while (0)
 
-/*
- * Non-SMP kernels will never block on the kernel lock,
- * so we are better off returning a constant zero from
- * reacquire_kernel_lock() so that the compiler can see
- * it at compile-time.
- */
-#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_BKL)
-# define return_value_on_smp return
-#else
-# define return_value_on_smp
-#endif
-
 static inline int reacquire_kernel_lock(struct task_struct *task)
 {
 	if (unlikely(task->lock_depth >= 0))
-		return_value_on_smp __reacquire_kernel_lock();
+		return __reacquire_kernel_lock();
 	return 0;
 }
 

kernel/Kconfig.preempt

@@ -52,10 +52,6 @@ config PREEMPT
 
 endchoice
 
-config PREEMPT_BKL
-	def_bool y
-	depends on SMP || PREEMPT
-
 config RCU_TRACE
 	bool "Enable tracing for RCU - currently stats in debugfs"
 	select DEBUG_FS

kernel/sched.c

@@ -3955,10 +3955,9 @@ EXPORT_SYMBOL(schedule);
 asmlinkage void __sched preempt_schedule(void)
 {
 	struct thread_info *ti = current_thread_info();
-#ifdef CONFIG_PREEMPT_BKL
 	struct task_struct *task = current;
 	int saved_lock_depth;
-#endif
+
 	/*
 	 * If there is a non-zero preempt_count or interrupts are disabled,
 	 * we do not want to preempt the current task. Just return..
@@ -3974,14 +3973,10 @@ asmlinkage void __sched preempt_schedule(void)
 		 * clear ->lock_depth so that schedule() doesnt
 		 * auto-release the semaphore:
 		 */
-#ifdef CONFIG_PREEMPT_BKL
 		saved_lock_depth = task->lock_depth;
 		task->lock_depth = -1;
-#endif
 		schedule();
-#ifdef CONFIG_PREEMPT_BKL
 		task->lock_depth = saved_lock_depth;
-#endif
 		sub_preempt_count(PREEMPT_ACTIVE);
 
 		/*
@@ -4002,10 +3997,9 @@ EXPORT_SYMBOL(preempt_schedule);
 asmlinkage void __sched preempt_schedule_irq(void)
 {
 	struct thread_info *ti = current_thread_info();
-#ifdef CONFIG_PREEMPT_BKL
 	struct task_struct *task = current;
 	int saved_lock_depth;
-#endif
+
 	/* Catch callers which need to be fixed */
 	BUG_ON(ti->preempt_count || !irqs_disabled());
 
@@ -4017,16 +4011,12 @@ asmlinkage void __sched preempt_schedule_irq(void)
 		 * clear ->lock_depth so that schedule() doesnt
 		 * auto-release the semaphore:
 		 */
-#ifdef CONFIG_PREEMPT_BKL
 		saved_lock_depth = task->lock_depth;
 		task->lock_depth = -1;
-#endif
 		local_irq_enable();
 		schedule();
 		local_irq_disable();
-#ifdef CONFIG_PREEMPT_BKL
 		task->lock_depth = saved_lock_depth;
-#endif
 		sub_preempt_count(PREEMPT_ACTIVE);
 
 		/*
@@ -5241,11 +5231,8 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
 	spin_unlock_irqrestore(&rq->lock, flags);
 
 	/* Set the preempt count _outside_ the spinlocks! */
-#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
-	task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
-#else
 	task_thread_info(idle)->preempt_count = 0;
-#endif
+
 	/*
 	 * The idle tasks have their own, simple scheduling class:
 	 */

lib/kernel_lock.c

@@ -9,7 +9,6 @@
 #include <linux/module.h>
 #include <linux/kallsyms.h>
 
-#ifdef CONFIG_PREEMPT_BKL
 /*
  * The 'big kernel semaphore'
  *
@@ -86,128 +85,6 @@ void __lockfunc unlock_kernel(void)
 		up(&kernel_sem);
 }
 
-#else
-
-/*
- * The 'big kernel lock'
- *
- * This spinlock is taken and released recursively by lock_kernel()
- * 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.
- *
- * Don't use in new code.
- */
-static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(kernel_flag);
-
-
-/*
- * Acquire/release the underlying lock from the scheduler.
- *
- * This is called with preemption disabled, and should
- * return an error value if it cannot get the lock and
- * TIF_NEED_RESCHED gets set.
- *
- * If it successfully gets the lock, it should increment
- * the preemption count like any spinlock does.
- *
- * (This works on UP too - _raw_spin_trylock will never
- * return false in that case)
- */
-int __lockfunc __reacquire_kernel_lock(void)
-{
-	while (!_raw_spin_trylock(&kernel_flag)) {
-		if (test_thread_flag(TIF_NEED_RESCHED))
-			return -EAGAIN;
-		cpu_relax();
-	}
-	preempt_disable();
-	return 0;
-}
-
-void __lockfunc __release_kernel_lock(void)
-{
-	_raw_spin_unlock(&kernel_flag);
-	preempt_enable_no_resched();
-}
-
-/*
- * 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.
- */
-#ifdef CONFIG_PREEMPT
-static inline void __lock_kernel(void)
-{
-	preempt_disable();
-	if (unlikely(!_raw_spin_trylock(&kernel_flag))) {
-		/*
-		 * If preemption was disabled even before this
-		 * was called, there's nothing we can be polite
-		 * about - just spin.
-		 */
-		if (preempt_count() > 1) {
-			_raw_spin_lock(&kernel_flag);
-			return;
-		}
-
-		/*
-		 * Otherwise, let's wait for the kernel lock
-		 * with preemption enabled..
-		 */
-		do {
-			preempt_enable();
-			while (spin_is_locked(&kernel_flag))
-				cpu_relax();
-			preempt_disable();
-		} while (!_raw_spin_trylock(&kernel_flag));
-	}
-}
-
-#else
-
-/*
- * Non-preemption case - just get the spinlock
- */
-static inline void __lock_kernel(void)
-{
-	_raw_spin_lock(&kernel_flag);
-}
-#endif
-
-static inline void __unlock_kernel(void)
-{
-	/*
-	 * 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();
-}
-
-/*
- * Getting the big kernel lock.
- *
- * This cannot happen asynchronously, so we only need to
- * worry about other CPU's.
- */
-void __lockfunc lock_kernel(void)
-{
-	int depth = current->lock_depth+1;
-	if (likely(!depth))
-		__lock_kernel();
-	current->lock_depth = depth;
-}
-
-void __lockfunc unlock_kernel(void)
-{
-	BUG_ON(current->lock_depth < 0);
-	if (likely(--current->lock_depth < 0))
-		__unlock_kernel();
-}
-
-#endif
-
 EXPORT_SYMBOL(lock_kernel);
 EXPORT_SYMBOL(unlock_kernel);