lockdep: Fix lockdep recursion
Steve reported that lockdep_assert*irq*(), when nested inside lockdep
itself, will trigger a false-positive.
One example is the stack-trace code, as called from inside lockdep,
triggering tracing, which in turn calls RCU, which then uses
lockdep_assert_irqs_disabled().
Fixes: a21ee6055c ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
Ingo Molnar
parent
2bb8945bcc
commit
4d004099a6
@ -534,6 +534,7 @@ do { \
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DECLARE_PER_CPU(int, hardirqs_enabled);
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DECLARE_PER_CPU(int, hardirq_context);
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DECLARE_PER_CPU(unsigned int, lockdep_recursion);
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/*
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* The below lockdep_assert_*() macros use raw_cpu_read() to access the above
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@ -543,25 +544,27 @@ DECLARE_PER_CPU(int, hardirq_context);
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* read the value from our previous CPU.
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*/
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#define __lockdep_enabled (debug_locks && !raw_cpu_read(lockdep_recursion))
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#define lockdep_assert_irqs_enabled() \
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do { \
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WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirqs_enabled)); \
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WARN_ON_ONCE(__lockdep_enabled && !raw_cpu_read(hardirqs_enabled)); \
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} while (0)
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#define lockdep_assert_irqs_disabled() \
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do { \
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WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled)); \
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WARN_ON_ONCE(__lockdep_enabled && raw_cpu_read(hardirqs_enabled)); \
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} while (0)
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#define lockdep_assert_in_irq() \
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do { \
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WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirq_context)); \
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WARN_ON_ONCE(__lockdep_enabled && !raw_cpu_read(hardirq_context)); \
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} while (0)
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#define lockdep_assert_preemption_enabled() \
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do { \
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WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
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debug_locks && \
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__lockdep_enabled && \
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(preempt_count() != 0 || \
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!raw_cpu_read(hardirqs_enabled))); \
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} while (0)
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@ -569,7 +572,7 @@ do { \
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#define lockdep_assert_preemption_disabled() \
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do { \
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WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT) && \
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debug_locks && \
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__lockdep_enabled && \
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(preempt_count() == 0 && \
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raw_cpu_read(hardirqs_enabled))); \
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} while (0)
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@ -76,6 +76,23 @@ module_param(lock_stat, int, 0644);
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#define lock_stat 0
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#endif
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DEFINE_PER_CPU(unsigned int, lockdep_recursion);
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EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
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static inline bool lockdep_enabled(void)
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{
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if (!debug_locks)
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return false;
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if (raw_cpu_read(lockdep_recursion))
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return false;
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if (current->lockdep_recursion)
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return false;
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return true;
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}
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/*
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* lockdep_lock: protects the lockdep graph, the hashes and the
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* class/list/hash allocators.
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@ -93,7 +110,7 @@ static inline void lockdep_lock(void)
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arch_spin_lock(&__lock);
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__owner = current;
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current->lockdep_recursion++;
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__this_cpu_inc(lockdep_recursion);
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}
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static inline void lockdep_unlock(void)
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@ -101,7 +118,7 @@ static inline void lockdep_unlock(void)
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if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
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return;
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current->lockdep_recursion--;
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__this_cpu_dec(lockdep_recursion);
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__owner = NULL;
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arch_spin_unlock(&__lock);
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}
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@ -393,10 +410,15 @@ void lockdep_init_task(struct task_struct *task)
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task->lockdep_recursion = 0;
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}
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static __always_inline void lockdep_recursion_inc(void)
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{
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__this_cpu_inc(lockdep_recursion);
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}
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static __always_inline void lockdep_recursion_finish(void)
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{
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if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK))
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current->lockdep_recursion = 0;
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if (WARN_ON_ONCE(__this_cpu_dec_return(lockdep_recursion)))
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__this_cpu_write(lockdep_recursion, 0);
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}
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void lockdep_set_selftest_task(struct task_struct *task)
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@ -3659,7 +3681,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
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if (unlikely(in_nmi()))
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return;
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if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
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if (unlikely(__this_cpu_read(lockdep_recursion)))
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return;
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if (unlikely(lockdep_hardirqs_enabled())) {
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@ -3695,7 +3717,7 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
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current->hardirq_chain_key = current->curr_chain_key;
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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__trace_hardirqs_on_caller();
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lockdep_recursion_finish();
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}
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@ -3728,7 +3750,7 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
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goto skip_checks;
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}
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if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
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if (unlikely(__this_cpu_read(lockdep_recursion)))
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return;
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if (lockdep_hardirqs_enabled()) {
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@ -3781,7 +3803,7 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
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if (in_nmi()) {
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if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
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return;
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} else if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
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} else if (__this_cpu_read(lockdep_recursion))
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return;
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/*
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@ -3814,7 +3836,7 @@ void lockdep_softirqs_on(unsigned long ip)
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{
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struct irqtrace_events *trace = ¤t->irqtrace;
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if (unlikely(!debug_locks || current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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/*
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@ -3829,7 +3851,7 @@ void lockdep_softirqs_on(unsigned long ip)
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return;
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}
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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/*
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* We'll do an OFF -> ON transition:
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*/
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@ -3852,7 +3874,7 @@ void lockdep_softirqs_on(unsigned long ip)
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*/
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void lockdep_softirqs_off(unsigned long ip)
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{
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if (unlikely(!debug_locks || current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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/*
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@ -4233,11 +4255,11 @@ void lockdep_init_map_waits(struct lockdep_map *lock, const char *name,
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if (subclass) {
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unsigned long flags;
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if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
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if (DEBUG_LOCKS_WARN_ON(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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register_lock_class(lock, subclass, 1);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -4920,11 +4942,11 @@ void lock_set_class(struct lockdep_map *lock, const char *name,
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{
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unsigned long flags;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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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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@ -4937,11 +4959,11 @@ void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
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{
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unsigned long flags;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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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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@ -4979,7 +5001,7 @@ static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock
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static bool lockdep_nmi(void)
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{
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if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
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if (raw_cpu_read(lockdep_recursion))
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return false;
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if (!in_nmi())
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@ -5000,7 +5022,10 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
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trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
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if (unlikely(current->lockdep_recursion)) {
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if (!debug_locks)
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return;
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if (unlikely(!lockdep_enabled())) {
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/* XXX allow trylock from NMI ?!? */
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if (lockdep_nmi() && !trylock) {
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struct held_lock hlock;
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@ -5023,7 +5048,7 @@ 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++;
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lockdep_recursion_inc();
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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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lockdep_recursion_finish();
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@ -5037,13 +5062,13 @@ void lock_release(struct lockdep_map *lock, unsigned long ip)
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trace_lock_release(lock, ip);
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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if (__lock_release(lock, ip))
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check_chain_key(current);
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lockdep_recursion_finish();
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@ -5056,13 +5081,13 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
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unsigned long flags;
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int ret = 0;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return 1; /* avoid false negative lockdep_assert_held() */
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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ret = __lock_is_held(lock, read);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -5077,13 +5102,13 @@ struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
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struct pin_cookie cookie = NIL_COOKIE;
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unsigned long flags;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return cookie;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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cookie = __lock_pin_lock(lock);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -5096,13 +5121,13 @@ void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
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{
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unsigned long flags;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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__lock_repin_lock(lock, cookie);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -5113,13 +5138,13 @@ void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
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{
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unsigned long flags;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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__lock_unpin_lock(lock, cookie);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -5249,15 +5274,12 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip)
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trace_lock_acquired(lock, ip);
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if (unlikely(!lock_stat || !debug_locks))
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return;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lock_stat || !lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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__lock_contended(lock, ip);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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@ -5270,15 +5292,12 @@ void lock_acquired(struct lockdep_map *lock, unsigned long ip)
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trace_lock_contended(lock, ip);
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if (unlikely(!lock_stat || !debug_locks))
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return;
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if (unlikely(current->lockdep_recursion))
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if (unlikely(!lock_stat || !lockdep_enabled()))
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return;
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raw_local_irq_save(flags);
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check_flags(flags);
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current->lockdep_recursion++;
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lockdep_recursion_inc();
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__lock_acquired(lock, ip);
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lockdep_recursion_finish();
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raw_local_irq_restore(flags);
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