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locking/lockdep: Rework lockdep_lock

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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: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200313102107.GX12561@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2020-03-13 11:09:49 +01:00
parent 10476e6304
commit 248efb2158
1 changed files with 48 additions and 41 deletions
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89
kernel/locking/lockdep.c
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@ -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);
}