locking/lockdep: Fix bad recursion pattern
There were two patterns for lockdep_recursion: Pattern-A: if (current->lockdep_recursion) return current->lockdep_recursion = 1; /* do stuff */ current->lockdep_recursion = 0; Pattern-B: current->lockdep_recursion++; /* do stuff */ current->lockdep_recursion--; But a third pattern has emerged: Pattern-C: current->lockdep_recursion = 1; /* do stuff */ current->lockdep_recursion = 0; And while this isn't broken per-se, it is highly dangerous because it doesn't nest properly. Get rid of all Pattern-C instances and shore up Pattern-A with a warning. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200313093325.GW12561@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra
parent
25016bd7f4
commit
10476e6304
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@ -390,6 +390,12 @@ void lockdep_on(void)
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}
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EXPORT_SYMBOL(lockdep_on);
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static inline void lockdep_recursion_finish(void)
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{
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if (WARN_ON_ONCE(--current->lockdep_recursion))
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current->lockdep_recursion = 0;
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}
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void lockdep_set_selftest_task(struct task_struct *task)
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{
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lockdep_selftest_task_struct = task;
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@ -1723,11 +1729,11 @@ unsigned long lockdep_count_forward_deps(struct lock_class *class)
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this.class = class;
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raw_local_irq_save(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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arch_spin_lock(&lockdep_lock);
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ret = __lockdep_count_forward_deps(&this);
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arch_spin_unlock(&lockdep_lock);
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current->lockdep_recursion = 0;
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current->lockdep_recursion--;
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raw_local_irq_restore(flags);
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return ret;
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@ -1752,11 +1758,11 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
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this.class = class;
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raw_local_irq_save(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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arch_spin_lock(&lockdep_lock);
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ret = __lockdep_count_backward_deps(&this);
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arch_spin_unlock(&lockdep_lock);
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current->lockdep_recursion = 0;
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current->lockdep_recursion--;
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raw_local_irq_restore(flags);
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return ret;
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@ -3668,9 +3674,9 @@ void lockdep_hardirqs_on(unsigned long ip)
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if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
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return;
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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__trace_hardirqs_on_caller(ip);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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}
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NOKPROBE_SYMBOL(lockdep_hardirqs_on);
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@ -3726,7 +3732,7 @@ void trace_softirqs_on(unsigned long ip)
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return;
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}
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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/*
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* We'll do an OFF -> ON transition:
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*/
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@ -3741,7 +3747,7 @@ void trace_softirqs_on(unsigned long ip)
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*/
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if (curr->hardirqs_enabled)
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mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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}
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/*
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@ -3995,9 +4001,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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register_lock_class(lock, subclass, 1);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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}
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@ -4677,11 +4683,11 @@ void lock_set_class(struct lockdep_map *lock, const char *name,
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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check_flags(flags);
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if (__lock_set_class(lock, name, key, subclass, ip))
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check_chain_key(current);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_set_class);
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@ -4694,11 +4700,11 @@ void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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check_flags(flags);
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if (__lock_downgrade(lock, ip))
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check_chain_key(current);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_downgrade);
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@ -4719,11 +4725,11 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
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__lock_acquire(lock, subclass, trylock, read, check,
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irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_acquire);
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@ -4737,11 +4743,11 @@ void lock_release(struct lockdep_map *lock, unsigned long ip)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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trace_lock_release(lock, ip);
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if (__lock_release(lock, ip))
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check_chain_key(current);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_release);
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@ -4757,9 +4763,9 @@ int lock_is_held_type(const struct lockdep_map *lock, int read)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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ret = __lock_is_held(lock, read);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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return ret;
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@ -4778,9 +4784,9 @@ struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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cookie = __lock_pin_lock(lock);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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return cookie;
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@ -4797,9 +4803,9 @@ void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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__lock_repin_lock(lock, cookie);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_repin_lock);
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@ -4814,9 +4820,9 @@ void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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__lock_unpin_lock(lock, cookie);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_unpin_lock);
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@ -4952,10 +4958,10 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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trace_lock_contended(lock, ip);
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__lock_contended(lock, ip);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_contended);
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@ -4972,9 +4978,9 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip)
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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__lock_acquired(lock, ip);
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current->lockdep_recursion = 0;
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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}
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EXPORT_SYMBOL_GPL(lock_acquired);
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@ -5176,7 +5182,7 @@ static void free_zapped_rcu(struct rcu_head *ch)
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raw_local_irq_save(flags);
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arch_spin_lock(&lockdep_lock);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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/* closed head */
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pf = delayed_free.pf + (delayed_free.index ^ 1);
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@ -5188,7 +5194,7 @@ static void free_zapped_rcu(struct rcu_head *ch)
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*/
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call_rcu_zapped(delayed_free.pf + delayed_free.index);
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current->lockdep_recursion = 0;
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current->lockdep_recursion--;
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arch_spin_unlock(&lockdep_lock);
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raw_local_irq_restore(flags);
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}
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@ -5235,11 +5241,11 @@ static void lockdep_free_key_range_reg(void *start, unsigned long size)
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raw_local_irq_save(flags);
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arch_spin_lock(&lockdep_lock);
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current->lockdep_recursion = 1;
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current->lockdep_recursion++;
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pf = get_pending_free();
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__lockdep_free_key_range(pf, start, size);
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call_rcu_zapped(pf);
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current->lockdep_recursion = 0;
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current->lockdep_recursion--;
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arch_spin_unlock(&lockdep_lock);
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raw_local_irq_restore(flags);
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