Commit bdd4e85d authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

sched: Isolate preempt counting in its own config option 



Create a new CONFIG_PREEMPT_COUNT that handles the inc/dec
of preempt count offset independently. So that the offset
can be updated by preempt_disable() and preempt_enable()
even without the need for CONFIG_PREEMPT beeing set.

This prepares to make CONFIG_DEBUG_SPINLOCK_SLEEP working
with !CONFIG_PREEMPT where it currently doesn't detect
code that sleeps inside explicit preemption disabled
sections.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
parent 2da8c8bc

include/linux/bit_spinlock.h

+1 −1
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) 
{

#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)

	return test_bit(bitnum, addr);

#elif defined CONFIG_PREEMPT

#elif defined CONFIG_PREEMPT_COUNT

	return preempt_count();

#else

	return 1;

include/linux/hardirq.h

+2 −2
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ 
 */

#define in_nmi()	(preempt_count() & NMI_MASK)



#if defined(CONFIG_PREEMPT)

#if defined(CONFIG_PREEMPT_COUNT)

# define PREEMPT_CHECK_OFFSET 1

#else

# define PREEMPT_CHECK_OFFSET 0
@@ -115,7 +115,7 @@ 
#define in_atomic_preempt_off() \

		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)



#ifdef CONFIG_PREEMPT

#ifdef CONFIG_PREEMPT_COUNT

# define preemptible()	(preempt_count() == 0 && !irqs_disabled())

# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)

#else

include/linux/pagemap.h

+2 −2
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ static inline int page_cache_get_speculative(struct page *page) 
	VM_BUG_ON(in_interrupt());



#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)

# ifdef CONFIG_PREEMPT

# ifdef CONFIG_PREEMPT_COUNT

	VM_BUG_ON(!in_atomic());

# endif

	/*
@@ -172,7 +172,7 @@ static inline int page_cache_add_speculative(struct page *page, int count) 
	VM_BUG_ON(in_interrupt());



#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)

# ifdef CONFIG_PREEMPT

# ifdef CONFIG_PREEMPT_COUNT

	VM_BUG_ON(!in_atomic());

# endif

	VM_BUG_ON(page_count(page) == 0);

include/linux/preempt.h

+17 −9
Original line number Diff line number Diff line
@@ -27,6 +27,21 @@ 


asmlinkage void preempt_schedule(void);



#define preempt_check_resched() \

do { \

	if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \

		preempt_schedule(); \

} while (0)



#else /* !CONFIG_PREEMPT */



#define preempt_check_resched()		do { } while (0)



#endif /* CONFIG_PREEMPT */





#ifdef CONFIG_PREEMPT_COUNT



#define preempt_disable() \

do { \

	inc_preempt_count(); \
@@ -39,12 +54,6 @@ do { \ 
	dec_preempt_count(); \

} while (0)



#define preempt_check_resched() \

do { \

	if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \

		preempt_schedule(); \

} while (0)



#define preempt_enable() \

do { \

	preempt_enable_no_resched(); \
@@ -80,18 +89,17 @@ do { \ 
	preempt_check_resched(); \

} while (0)



#else

#else /* !CONFIG_PREEMPT_COUNT */



#define preempt_disable()		do { } while (0)

#define preempt_enable_no_resched()	do { } while (0)

#define preempt_enable()		do { } while (0)

#define preempt_check_resched()		do { } while (0)



#define preempt_disable_notrace()		do { } while (0)

#define preempt_enable_no_resched_notrace()	do { } while (0)

#define preempt_enable_notrace()		do { } while (0)



#endif

#endif /* CONFIG_PREEMPT_COUNT */



#ifdef CONFIG_PREEMPT_NOTIFIERS

include/linux/rcupdate.h

+6 −6
Original line number Diff line number Diff line
@@ -239,7 +239,7 @@ extern int rcu_read_lock_bh_held(void); 
 * Check debug_lockdep_rcu_enabled() to prevent false positives during boot

 * and while lockdep is disabled.

 */

#ifdef CONFIG_PREEMPT

#ifdef CONFIG_PREEMPT_COUNT

static inline int rcu_read_lock_sched_held(void)

{

	int lockdep_opinion = 0;
@@ -250,12 +250,12 @@ static inline int rcu_read_lock_sched_held(void) 
		lockdep_opinion = lock_is_held(&rcu_sched_lock_map);

	return lockdep_opinion || preempt_count() != 0 || irqs_disabled();

}

#else /* #ifdef CONFIG_PREEMPT */

#else /* #ifdef CONFIG_PREEMPT_COUNT */

static inline int rcu_read_lock_sched_held(void)

{

	return 1;

}

#endif /* #else #ifdef CONFIG_PREEMPT */

#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */



#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
@@ -276,17 +276,17 @@ static inline int rcu_read_lock_bh_held(void) 
	return 1;

}



#ifdef CONFIG_PREEMPT

#ifdef CONFIG_PREEMPT_COUNT

static inline int rcu_read_lock_sched_held(void)

{

	return preempt_count() != 0 || irqs_disabled();

}

#else /* #ifdef CONFIG_PREEMPT */

#else /* #ifdef CONFIG_PREEMPT_COUNT */

static inline int rcu_read_lock_sched_held(void)

{

	return 1;

}

#endif /* #else #ifdef CONFIG_PREEMPT */

#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */



#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

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