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When dumping lock_classes information via /proc/lockdep, we can't take the lockdep lock as the lock hold time is indeterminate. Iterating over all_lock_classes without holding lock can be dangerous as there is a slight chance that it may branch off to other lists leading to infinite loop or even access invalid memory if changes are made to all_lock_classes list in parallel. To avoid this problem, iteration of lock classes is now done directly on the lock_classes array itself. The lock_classes_in_use bitmap is checked to see if the lock class is being used. To avoid iterating the full array all the times, a new max_lock_class_idx value is added to track the maximum lock_class index that is currently being used. We can theoretically take the lockdep lock for iterating all_lock_classes when other lockdep files (lockdep_stats and lock_stat) are accessed as the lock hold time will be shorter for them. For consistency, they are also modified to iterate the lock_classes array directly. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220211035526.1329503-2-longman@redhat.com
261 lines
7.3 KiB
C
261 lines
7.3 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_USED_READ,
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LOCK_USAGE_STATES,
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};
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/* states after LOCK_USED_READ are not traced and printed */
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static_assert(LOCK_TRACE_STATES == LOCK_USAGE_STATES);
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#define LOCK_USAGE_READ_MASK 1
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#define LOCK_USAGE_DIR_MASK 2
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#define LOCK_USAGE_STATE_MASK (~(LOCK_USAGE_READ_MASK | LOCK_USAGE_DIR_MASK))
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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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__LOCKF(USED_READ)
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};
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#define LOCKDEP_STATE(__STATE) LOCKF_ENABLED_##__STATE |
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static const unsigned long LOCKF_ENABLED_IRQ =
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#include "lockdep_states.h"
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0;
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#undef LOCKDEP_STATE
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#define LOCKDEP_STATE(__STATE) LOCKF_USED_IN_##__STATE |
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static const unsigned long LOCKF_USED_IN_IRQ =
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#include "lockdep_states.h"
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0;
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#undef LOCKDEP_STATE
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#define LOCKDEP_STATE(__STATE) LOCKF_ENABLED_##__STATE##_READ |
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static const unsigned long LOCKF_ENABLED_IRQ_READ =
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#include "lockdep_states.h"
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0;
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#undef LOCKDEP_STATE
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#define LOCKDEP_STATE(__STATE) LOCKF_USED_IN_##__STATE##_READ |
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static const unsigned long LOCKF_USED_IN_IRQ_READ =
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#include "lockdep_states.h"
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0;
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#undef LOCKDEP_STATE
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#define LOCKF_ENABLED_IRQ_ALL (LOCKF_ENABLED_IRQ | LOCKF_ENABLED_IRQ_READ)
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#define LOCKF_USED_IN_IRQ_ALL (LOCKF_USED_IN_IRQ | LOCKF_USED_IN_IRQ_READ)
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#define LOCKF_IRQ (LOCKF_ENABLED_IRQ | LOCKF_USED_IN_IRQ)
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#define LOCKF_IRQ_READ (LOCKF_ENABLED_IRQ_READ | LOCKF_USED_IN_IRQ_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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#define STACK_TRACE_HASH_SIZE 8192
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#else
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#define MAX_LOCKDEP_ENTRIES (1UL << CONFIG_LOCKDEP_BITS)
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#define MAX_LOCKDEP_CHAINS_BITS CONFIG_LOCKDEP_CHAINS_BITS
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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 (1UL << CONFIG_LOCKDEP_STACK_TRACE_BITS)
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#define STACK_TRACE_HASH_SIZE (1 << CONFIG_LOCKDEP_STACK_TRACE_HASH_BITS)
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#endif
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/*
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* Bit definitions for lock_chain.irq_context
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*/
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#define LOCK_CHAIN_SOFTIRQ_CONTEXT (1 << 0)
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#define LOCK_CHAIN_HARDIRQ_CONTEXT (1 << 1)
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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 lock_chain lock_chains[];
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#define LOCK_USAGE_CHARS (2*XXX_LOCK_USAGE_STATES + 1)
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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(const struct lockdep_subclass_key *key,
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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_zapped_classes;
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extern unsigned long nr_zapped_lock_chains;
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extern unsigned long nr_list_entries;
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long lockdep_next_lockchain(long i);
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unsigned long lock_chain_count(void);
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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 nr_free_chain_hlocks;
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extern unsigned int nr_lost_chain_hlocks;
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extern unsigned int nr_large_chain_blocks;
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extern unsigned int max_lockdep_depth;
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extern unsigned int max_bfs_queue_depth;
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extern unsigned long max_lock_class_idx;
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extern struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
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extern unsigned long lock_classes_in_use[];
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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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#ifdef CONFIG_TRACE_IRQFLAGS
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u64 lockdep_stack_trace_count(void);
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u64 lockdep_stack_hash_count(void);
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#endif
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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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unsigned long chain_lookup_hits;
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unsigned int chain_lookup_misses;
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unsigned long hardirqs_on_events;
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unsigned long hardirqs_off_events;
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unsigned long redundant_hardirqs_on;
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unsigned long redundant_hardirqs_off;
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unsigned long softirqs_on_events;
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unsigned long softirqs_off_events;
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unsigned long redundant_softirqs_on;
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unsigned long redundant_softirqs_off;
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int nr_unused_locks;
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unsigned int nr_redundant_checks;
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unsigned int nr_redundant;
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unsigned int nr_cyclic_checks;
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unsigned int nr_find_usage_forwards_checks;
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unsigned int nr_find_usage_backwards_checks;
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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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#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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