Commit 248efb21 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

locking/lockdep: Rework lockdep_lock 



A few sites want to assert we own the graph_lock/lockdep_lock, provide
a more conventional lock interface for it with a number of trivial
debug checks.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200313102107.GX12561@hirez.programming.kicks-ass.net
parent 10476e63

kernel/locking/lockdep.c

+48 −41
Original line number Diff line number Diff line
@@ -84,12 +84,39 @@ module_param(lock_stat, int, 0644); 
 * to use a raw spinlock - we really dont want the spinlock

 * code to recurse back into the lockdep code...

 */

static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;

static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;

static struct task_struct *__owner;



static inline void lockdep_lock(void)

{

	DEBUG_LOCKS_WARN_ON(!irqs_disabled());



	arch_spin_lock(&__lock);

	__owner = current;

	current->lockdep_recursion++;

}



static inline void lockdep_unlock(void)

{

	if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))

		return;



	current->lockdep_recursion--;

	__owner = NULL;

	arch_spin_unlock(&__lock);

}



static inline bool lockdep_assert_locked(void)

{

	return DEBUG_LOCKS_WARN_ON(__owner != current);

}



static struct task_struct *lockdep_selftest_task_struct;





static int graph_lock(void)

{

	arch_spin_lock(&lockdep_lock);

	lockdep_lock();

	/*

	 * Make sure that if another CPU detected a bug while

	 * walking the graph we dont change it (while the other
@@ -97,27 +124,15 @@ static int graph_lock(void) 
	 * dropped already)

	 */

	if (!debug_locks) {

		arch_spin_unlock(&lockdep_lock);

		lockdep_unlock();

		return 0;

	}

	/* prevent any recursions within lockdep from causing deadlocks */

	current->lockdep_recursion++;

	return 1;

}



static inline int graph_unlock(void)

static inline void graph_unlock(void)

{

	if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {

		/*

		 * The lockdep graph lock isn't locked while we expect it to

		 * be, we're confused now, bye!

		 */

		return DEBUG_LOCKS_WARN_ON(1);

	}



	current->lockdep_recursion--;

	arch_spin_unlock(&lockdep_lock);

	return 0;

	lockdep_unlock();

}



/*
@@ -128,7 +143,7 @@ static inline int debug_locks_off_graph_unlock(void) 
{

	int ret = debug_locks_off();



	arch_spin_unlock(&lockdep_lock);

	lockdep_unlock();



	return ret;

}
@@ -1479,6 +1494,8 @@ static int __bfs(struct lock_list *source_entry, 
	struct circular_queue *cq = &lock_cq;

	int ret = 1;



	lockdep_assert_locked();



	if (match(source_entry, data)) {

		*target_entry = source_entry;

		ret = 0;
@@ -1501,8 +1518,6 @@ static int __bfs(struct lock_list *source_entry, 


		head = get_dep_list(lock, offset);



		DEBUG_LOCKS_WARN_ON(!irqs_disabled());



		list_for_each_entry_rcu(entry, head, entry) {

			if (!lock_accessed(entry)) {

				unsigned int cq_depth;
@@ -1729,11 +1744,9 @@ unsigned long lockdep_count_forward_deps(struct lock_class *class) 
	this.class = class;



	raw_local_irq_save(flags);

	current->lockdep_recursion++;

	arch_spin_lock(&lockdep_lock);

	lockdep_lock();

	ret = __lockdep_count_forward_deps(&this);

	arch_spin_unlock(&lockdep_lock);

	current->lockdep_recursion--;

	lockdep_unlock();

	raw_local_irq_restore(flags);



	return ret;
@@ -1758,11 +1771,9 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) 
	this.class = class;



	raw_local_irq_save(flags);

	current->lockdep_recursion++;

	arch_spin_lock(&lockdep_lock);

	lockdep_lock();

	ret = __lockdep_count_backward_deps(&this);

	arch_spin_unlock(&lockdep_lock);

	current->lockdep_recursion--;

	lockdep_unlock();

	raw_local_irq_restore(flags);



	return ret;
@@ -3046,7 +3057,7 @@ static inline int add_chain_cache(struct task_struct *curr, 
	 * disabled to make this an IRQ-safe lock.. for recursion reasons

	 * lockdep won't complain about its own locking errors.

	 */

	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))

	if (lockdep_assert_locked())

		return 0;



	chain = alloc_lock_chain();
@@ -5181,8 +5192,7 @@ static void free_zapped_rcu(struct rcu_head *ch) 
		return;



	raw_local_irq_save(flags);

	arch_spin_lock(&lockdep_lock);

	current->lockdep_recursion++;

	lockdep_lock();



	/* closed head */

	pf = delayed_free.pf + (delayed_free.index ^ 1);
@@ -5194,8 +5204,7 @@ static void free_zapped_rcu(struct rcu_head *ch) 
	 */

	call_rcu_zapped(delayed_free.pf + delayed_free.index);



	current->lockdep_recursion--;

	arch_spin_unlock(&lockdep_lock);

	lockdep_unlock();

	raw_local_irq_restore(flags);

}
@@ -5240,13 +5249,11 @@ static void lockdep_free_key_range_reg(void *start, unsigned long size) 
	init_data_structures_once();



	raw_local_irq_save(flags);

	arch_spin_lock(&lockdep_lock);

	current->lockdep_recursion++;

	lockdep_lock();

	pf = get_pending_free();

	__lockdep_free_key_range(pf, start, size);

	call_rcu_zapped(pf);

	current->lockdep_recursion--;

	arch_spin_unlock(&lockdep_lock);

	lockdep_unlock();

	raw_local_irq_restore(flags);



	/*
@@ -5268,10 +5275,10 @@ static void lockdep_free_key_range_imm(void *start, unsigned long size) 
	init_data_structures_once();



	raw_local_irq_save(flags);

	arch_spin_lock(&lockdep_lock);

	lockdep_lock();

	__lockdep_free_key_range(pf, start, size);

	__free_zapped_classes(pf);

	arch_spin_unlock(&lockdep_lock);

	lockdep_unlock();

	raw_local_irq_restore(flags);

}
@@ -5367,10 +5374,10 @@ static void lockdep_reset_lock_imm(struct lockdep_map *lock) 
	unsigned long flags;



	raw_local_irq_save(flags);

	arch_spin_lock(&lockdep_lock);

	lockdep_lock();

	__lockdep_reset_lock(pf, lock);

	__free_zapped_classes(pf);

	arch_spin_unlock(&lockdep_lock);

	lockdep_unlock();

	raw_local_irq_restore(flags);

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE