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8ca2b56cd7
A sizable portion of the CPU cycles spent on the __lock_acquire() is used up by the atomic increment of the class->ops stat counter. By taking it out from the lock_class structure and changing it to a per-cpu per-lock-class counter, we can reduce the amount of cacheline contention on the class structure when multiple CPUs are trying to acquire locks of the same class simultaneously. To limit the increase in memory consumption because of the percpu nature of that counter, it is now put back under the CONFIG_DEBUG_LOCKDEP config option. So the memory consumption increase will only occur if CONFIG_DEBUG_LOCKDEP is defined. The lock_class structure, however, is reduced in size by 16 bytes on 64-bit archs after ops removal and a minor restructuring of the fields. This patch also fixes a bug in the increment code as the counter is of the 'unsigned long' type, but atomic_inc() was used to increment it. Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/r/d66681f3-8781-9793-1dcf-2436a284550b@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
214 lines
5.7 KiB
C
214 lines
5.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* kernel/lockdep_internals.h
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*
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* Runtime locking correctness validator
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*
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* lockdep subsystem internal functions and variables.
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*/
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/*
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* Lock-class usage-state bits:
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*/
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enum lock_usage_bit {
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#define LOCKDEP_STATE(__STATE) \
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LOCK_USED_IN_##__STATE, \
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LOCK_USED_IN_##__STATE##_READ, \
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LOCK_ENABLED_##__STATE, \
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LOCK_ENABLED_##__STATE##_READ,
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#include "lockdep_states.h"
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#undef LOCKDEP_STATE
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LOCK_USED,
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LOCK_USAGE_STATES
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};
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/*
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* Usage-state bitmasks:
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*/
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#define __LOCKF(__STATE) LOCKF_##__STATE = (1 << LOCK_##__STATE),
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enum {
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#define LOCKDEP_STATE(__STATE) \
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__LOCKF(USED_IN_##__STATE) \
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__LOCKF(USED_IN_##__STATE##_READ) \
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__LOCKF(ENABLED_##__STATE) \
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__LOCKF(ENABLED_##__STATE##_READ)
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#include "lockdep_states.h"
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#undef LOCKDEP_STATE
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__LOCKF(USED)
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};
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#define LOCKF_ENABLED_IRQ (LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ)
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#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
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#define LOCKF_ENABLED_IRQ_READ \
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(LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ)
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#define LOCKF_USED_IN_IRQ_READ \
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(LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
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/*
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* CONFIG_LOCKDEP_SMALL is defined for sparc. Sparc requires .text,
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* .data and .bss to fit in required 32MB limit for the kernel. With
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* CONFIG_LOCKDEP we could go over this limit and cause system boot-up problems.
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* So, reduce the static allocations for lockdeps related structures so that
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* everything fits in current required size limit.
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*/
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#ifdef CONFIG_LOCKDEP_SMALL
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/*
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* MAX_LOCKDEP_ENTRIES is the maximum number of lock dependencies
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* we track.
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*
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* We use the per-lock dependency maps in two ways: we grow it by adding
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* every to-be-taken lock to all currently held lock's own dependency
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* table (if it's not there yet), and we check it for lock order
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* conflicts and deadlocks.
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*/
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#define MAX_LOCKDEP_ENTRIES 16384UL
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#define MAX_LOCKDEP_CHAINS_BITS 15
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#define MAX_STACK_TRACE_ENTRIES 262144UL
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#else
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#define MAX_LOCKDEP_ENTRIES 32768UL
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#define MAX_LOCKDEP_CHAINS_BITS 16
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/*
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* Stack-trace: tightly packed array of stack backtrace
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* addresses. Protected by the hash_lock.
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*/
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#define MAX_STACK_TRACE_ENTRIES 524288UL
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#endif
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#define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS)
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#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
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extern struct list_head all_lock_classes;
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extern struct lock_chain lock_chains[];
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#define LOCK_USAGE_CHARS (1+LOCK_USAGE_STATES/2)
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extern void get_usage_chars(struct lock_class *class,
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char usage[LOCK_USAGE_CHARS]);
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extern const char * __get_key_name(struct lockdep_subclass_key *key, char *str);
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struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i);
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extern unsigned long nr_lock_classes;
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extern unsigned long nr_list_entries;
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extern unsigned long nr_lock_chains;
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extern int nr_chain_hlocks;
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extern unsigned long nr_stack_trace_entries;
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extern unsigned int nr_hardirq_chains;
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extern unsigned int nr_softirq_chains;
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extern unsigned int nr_process_chains;
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extern unsigned int max_lockdep_depth;
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extern unsigned int max_recursion_depth;
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extern unsigned int max_bfs_queue_depth;
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#ifdef CONFIG_PROVE_LOCKING
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extern unsigned long lockdep_count_forward_deps(struct lock_class *);
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extern unsigned long lockdep_count_backward_deps(struct lock_class *);
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#else
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static inline unsigned long
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lockdep_count_forward_deps(struct lock_class *class)
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{
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return 0;
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}
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static inline unsigned long
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lockdep_count_backward_deps(struct lock_class *class)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_DEBUG_LOCKDEP
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#include <asm/local.h>
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/*
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* Various lockdep statistics.
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* We want them per cpu as they are often accessed in fast path
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* and we want to avoid too much cache bouncing.
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*/
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struct lockdep_stats {
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int chain_lookup_hits;
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int chain_lookup_misses;
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int hardirqs_on_events;
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int hardirqs_off_events;
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int redundant_hardirqs_on;
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int redundant_hardirqs_off;
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int softirqs_on_events;
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int softirqs_off_events;
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int redundant_softirqs_on;
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int redundant_softirqs_off;
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int nr_unused_locks;
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int nr_redundant_checks;
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int nr_redundant;
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int nr_cyclic_checks;
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int nr_cyclic_check_recursions;
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int nr_find_usage_forwards_checks;
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int nr_find_usage_forwards_recursions;
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int nr_find_usage_backwards_checks;
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int nr_find_usage_backwards_recursions;
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/*
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* Per lock class locking operation stat counts
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*/
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unsigned long lock_class_ops[MAX_LOCKDEP_KEYS];
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};
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DECLARE_PER_CPU(struct lockdep_stats, lockdep_stats);
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extern struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
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#define __debug_atomic_inc(ptr) \
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this_cpu_inc(lockdep_stats.ptr);
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#define debug_atomic_inc(ptr) { \
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WARN_ON_ONCE(!irqs_disabled()); \
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__this_cpu_inc(lockdep_stats.ptr); \
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}
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#define debug_atomic_dec(ptr) { \
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WARN_ON_ONCE(!irqs_disabled()); \
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__this_cpu_dec(lockdep_stats.ptr); \
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}
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#define debug_atomic_read(ptr) ({ \
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struct lockdep_stats *__cpu_lockdep_stats; \
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unsigned long long __total = 0; \
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int __cpu; \
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for_each_possible_cpu(__cpu) { \
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__cpu_lockdep_stats = &per_cpu(lockdep_stats, __cpu); \
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__total += __cpu_lockdep_stats->ptr; \
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} \
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__total; \
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})
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static inline void debug_class_ops_inc(struct lock_class *class)
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{
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int idx;
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idx = class - lock_classes;
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__debug_atomic_inc(lock_class_ops[idx]);
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}
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static inline unsigned long debug_class_ops_read(struct lock_class *class)
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{
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int idx, cpu;
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unsigned long ops = 0;
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idx = class - lock_classes;
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for_each_possible_cpu(cpu)
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ops += per_cpu(lockdep_stats.lock_class_ops[idx], cpu);
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return ops;
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}
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#else
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# define __debug_atomic_inc(ptr) do { } while (0)
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# define debug_atomic_inc(ptr) do { } while (0)
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# define debug_atomic_dec(ptr) do { } while (0)
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# define debug_atomic_read(ptr) 0
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# define debug_class_ops_inc(ptr) do { } while (0)
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#endif
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