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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#define pr_fmt(fmt) "stackdepot: " fmt
#include <linux/debugfs.h>#include <linux/gfp.h>#include <linux/jhash.h>#include <linux/kernel.h>#include <linux/kmsan.h>#include <linux/list.h>#include <linux/mm.h>#include <linux/mutex.h>#include <linux/poison.h>#include <linux/printk.h>#include <linux/rculist.h>#include <linux/rcupdate.h>#include <linux/refcount.h>#include <linux/slab.h>#include <linux/spinlock.h>#include <linux/stacktrace.h>#include <linux/stackdepot.h>#include <linux/string.h>#include <linux/types.h>#include <linux/memblock.h>#include <linux/kasan-enabled.h>
/* * The pool_index is offset by 1 so the first record does not have a 0 handle. */static unsigned int stack_max_pools __read_mostly = MIN((1LL << DEPOT_POOL_INDEX_BITS) - 1, 8192);
static bool stack_depot_disabled;static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);static bool __stack_depot_early_init_passed __initdata;
/* Use one hash table bucket per 16 KB of memory. */#define STACK_HASH_TABLE_SCALE 14/* Limit the number of buckets between 4K and 1M. */#define STACK_BUCKET_NUMBER_ORDER_MIN 12#define STACK_BUCKET_NUMBER_ORDER_MAX 20/* Initial seed for jhash2. */#define STACK_HASH_SEED 0x9747b28c
/* Hash table of stored stack records. */static struct list_head *stack_table;/* Fixed order of the number of table buckets. Used when KASAN is enabled. */static unsigned int stack_bucket_number_order;/* Hash mask for indexing the table. */static unsigned int stack_hash_mask;
/* The lock must be held when performing pool or freelist modifications. */static DEFINE_RAW_SPINLOCK(pool_lock);/* Array of memory regions that store stack records. */static void **stack_pools __pt_guarded_by(&pool_lock);/* Newly allocated pool that is not yet added to stack_pools. */static void *new_pool;/* Number of pools in stack_pools. */static int pools_num;/* Offset to the unused space in the currently used pool. */static size_t pool_offset __guarded_by(&pool_lock) = DEPOT_POOL_SIZE;/* Freelist of stack records within stack_pools. */static __guarded_by(&pool_lock) LIST_HEAD(free_stacks);
/* Statistics counters for debugfs. */enum depot_counter_id { DEPOT_COUNTER_REFD_ALLOCS, DEPOT_COUNTER_REFD_FREES, DEPOT_COUNTER_REFD_INUSE, DEPOT_COUNTER_FREELIST_SIZE, DEPOT_COUNTER_PERSIST_COUNT, DEPOT_COUNTER_PERSIST_BYTES, DEPOT_COUNTER_COUNT,};static long counters[DEPOT_COUNTER_COUNT];static const char *const counter_names[] = { [DEPOT_COUNTER_REFD_ALLOCS] = "refcounted_allocations", [DEPOT_COUNTER_REFD_FREES] = "refcounted_frees", [DEPOT_COUNTER_REFD_INUSE] = "refcounted_in_use", [DEPOT_COUNTER_FREELIST_SIZE] = "freelist_size", [DEPOT_COUNTER_PERSIST_COUNT] = "persistent_count", [DEPOT_COUNTER_PERSIST_BYTES] = "persistent_bytes",};static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT);
static int __init disable_stack_depot(char *str){ return kstrtobool(str, &stack_depot_disabled);}early_param("stack_depot_disable", disable_stack_depot);
static int __init parse_max_pools(char *str){ const long long limit = (1LL << (DEPOT_POOL_INDEX_BITS)) - 1; unsigned int max_pools; int rv;
rv = kstrtouint(str, 0, &max_pools); if (rv) return rv;
if (max_pools < 1024) { pr_err("stack_depot_max_pools below 1024, using default of %u\n", stack_max_pools); goto out; }
if (max_pools > limit) { pr_err("stack_depot_max_pools exceeds %lld, using default of %u\n", limit, stack_max_pools); goto out; }
stack_max_pools = max_pools;out: return 0;}early_param("stack_depot_max_pools", parse_max_pools);
void __init stack_depot_request_early_init(void){ /* Too late to request early init now. */ WARN_ON(__stack_depot_early_init_passed);
__stack_depot_early_init_requested = true;}
/* Initialize list_head's within the hash table. */static void init_stack_table(unsigned long entries){ unsigned long i;
for (i = 0; i < entries; i++) INIT_LIST_HEAD(&stack_table[i]);}
/* Allocates a hash table via memblock. Can only be used during early boot. */int __init stack_depot_early_init(void){ unsigned long entries = 0;
/* This function must be called only once, from mm_init(). */ if (WARN_ON(__stack_depot_early_init_passed)) return 0; __stack_depot_early_init_passed = true;
/* * Print disabled message even if early init has not been requested: * stack_depot_init() will not print one. */ if (stack_depot_disabled) { pr_info("disabled\n"); return 0; }
/* * If KASAN is enabled, use the maximum order: KASAN is frequently used * in fuzzing scenarios, which leads to a large number of different * stack traces being stored in stack depot. */ if (kasan_enabled() && !stack_bucket_number_order) stack_bucket_number_order = STACK_BUCKET_NUMBER_ORDER_MAX;
/* * Check if early init has been requested after setting * stack_bucket_number_order: stack_depot_init() uses its value. */ if (!__stack_depot_early_init_requested) return 0;
/* * If stack_bucket_number_order is not set, leave entries as 0 to rely * on the automatic calculations performed by alloc_large_system_hash(). */ if (stack_bucket_number_order) entries = 1UL << stack_bucket_number_order; pr_info("allocating hash table via alloc_large_system_hash\n"); stack_table = alloc_large_system_hash("stackdepot", sizeof(struct list_head), entries, STACK_HASH_TABLE_SCALE, HASH_EARLY, NULL, &stack_hash_mask, 1UL << STACK_BUCKET_NUMBER_ORDER_MIN, 1UL << STACK_BUCKET_NUMBER_ORDER_MAX); if (!stack_table) { pr_err("hash table allocation failed, disabling\n"); stack_depot_disabled = true; return -ENOMEM; } if (!entries) { /* * Obtain the number of entries that was calculated by * alloc_large_system_hash(). */ entries = stack_hash_mask + 1; } init_stack_table(entries);
pr_info("allocating space for %u stack pools via memblock\n", stack_max_pools); stack_pools = memblock_alloc(stack_max_pools * sizeof(void *), PAGE_SIZE); if (!stack_pools) { pr_err("stack pools allocation failed, disabling\n"); memblock_free(stack_table, entries * sizeof(struct list_head)); stack_depot_disabled = true; return -ENOMEM; }
return 0;}
/* Allocates a hash table via kvcalloc. Can be used after boot. */int stack_depot_init(void){ static DEFINE_MUTEX(stack_depot_init_mutex); unsigned long entries; int ret = 0;
mutex_lock(&stack_depot_init_mutex);
if (stack_depot_disabled || stack_table) goto out_unlock;
/* * Similarly to stack_depot_early_init, use stack_bucket_number_order * if assigned, and rely on automatic scaling otherwise. */ if (stack_bucket_number_order) { entries = 1UL << stack_bucket_number_order; } else { int scale = STACK_HASH_TABLE_SCALE;
entries = nr_free_buffer_pages(); entries = roundup_pow_of_two(entries);
if (scale > PAGE_SHIFT) entries >>= (scale - PAGE_SHIFT); else entries <<= (PAGE_SHIFT - scale); }
if (entries < 1UL << STACK_BUCKET_NUMBER_ORDER_MIN) entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MIN; if (entries > 1UL << STACK_BUCKET_NUMBER_ORDER_MAX) entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MAX;
pr_info("allocating hash table of %lu entries via kvcalloc\n", entries); stack_table = kvzalloc_objs(struct list_head, entries); if (!stack_table) { pr_err("hash table allocation failed, disabling\n"); stack_depot_disabled = true; ret = -ENOMEM; goto out_unlock; } stack_hash_mask = entries - 1; init_stack_table(entries);
pr_info("allocating space for %u stack pools via kvcalloc\n", stack_max_pools); stack_pools = kvcalloc(stack_max_pools, sizeof(void *), GFP_KERNEL); if (!stack_pools) { pr_err("stack pools allocation failed, disabling\n"); kvfree(stack_table); stack_depot_disabled = true; ret = -ENOMEM; }
out_unlock: mutex_unlock(&stack_depot_init_mutex);
return ret;}EXPORT_SYMBOL_GPL(stack_depot_init);
/* * Initializes new stack pool, and updates the list of pools. */static bool depot_init_pool(void **prealloc) __must_hold(&pool_lock){ lockdep_assert_held(&pool_lock);
if (unlikely(pools_num >= stack_max_pools)) { /* Bail out if we reached the pool limit. */ WARN_ON_ONCE(pools_num > stack_max_pools); /* should never happen */ WARN_ON_ONCE(!new_pool); /* to avoid unnecessary pre-allocation */ WARN_ONCE(1, "Stack depot reached limit capacity"); return false; }
if (!new_pool && *prealloc) { /* We have preallocated memory, use it. */ WRITE_ONCE(new_pool, *prealloc); *prealloc = NULL; }
if (!new_pool) return false; /* new_pool and *prealloc are NULL */
/* Save reference to the pool to be used by depot_fetch_stack(). */ stack_pools[pools_num] = new_pool;
/* * Stack depot tries to keep an extra pool allocated even before it runs * out of space in the currently used pool. * * To indicate that a new preallocation is needed new_pool is reset to * NULL; do not reset to NULL if we have reached the maximum number of * pools. */ if (pools_num + 1 < stack_max_pools) WRITE_ONCE(new_pool, NULL); else WRITE_ONCE(new_pool, STACK_DEPOT_POISON);
/* Pairs with concurrent READ_ONCE() in depot_fetch_stack(). */ WRITE_ONCE(pools_num, pools_num + 1); ASSERT_EXCLUSIVE_WRITER(pools_num);
pool_offset = 0;
return true;}
/* Keeps the preallocated memory to be used for a new stack depot pool. */static void depot_keep_new_pool(void **prealloc) __must_hold(&pool_lock){ lockdep_assert_held(&pool_lock);
/* * If a new pool is already saved or the maximum number of * pools is reached, do not use the preallocated memory. */ if (new_pool) return;
WRITE_ONCE(new_pool, *prealloc); *prealloc = NULL;}
/* * Try to initialize a new stack record from the current pool, a cached pool, or * the current pre-allocation. */static struct stack_record *depot_pop_free_pool(void **prealloc, size_t size) __must_hold(&pool_lock){ struct stack_record *stack; void *current_pool; u32 pool_index;
lockdep_assert_held(&pool_lock);
if (pool_offset + size > DEPOT_POOL_SIZE) { if (!depot_init_pool(prealloc)) return NULL; }
if (WARN_ON_ONCE(pools_num < 1)) return NULL; pool_index = pools_num - 1; current_pool = stack_pools[pool_index]; if (WARN_ON_ONCE(!current_pool)) return NULL;
stack = current_pool + pool_offset;
/* Pre-initialize handle once. */ stack->handle.pool_index_plus_1 = pool_index + 1; stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN; stack->handle.extra = 0; INIT_LIST_HEAD(&stack->hash_list);
pool_offset += size;
return stack;}
/* Try to find next free usable entry from the freelist. */static struct stack_record *depot_pop_free(void) __must_hold(&pool_lock){ struct stack_record *stack;
lockdep_assert_held(&pool_lock);
if (list_empty(&free_stacks)) return NULL;
/* * We maintain the invariant that the elements in front are least * recently used, and are therefore more likely to be associated with an * RCU grace period in the past. Consequently it is sufficient to only * check the first entry. */ stack = list_first_entry(&free_stacks, struct stack_record, free_list); if (!poll_state_synchronize_rcu(stack->rcu_state)) return NULL;
list_del(&stack->free_list); counters[DEPOT_COUNTER_FREELIST_SIZE]--;
return stack;}
static inline size_t depot_stack_record_size(struct stack_record *s, unsigned int nr_entries){ const size_t used = flex_array_size(s, entries, nr_entries); const size_t unused = sizeof(s->entries) - used;
WARN_ON_ONCE(sizeof(s->entries) < used);
return ALIGN(sizeof(struct stack_record) - unused, 1 << DEPOT_STACK_ALIGN);}
/* Allocates a new stack in a stack depot pool. */static struct stack_record *depot_alloc_stack(unsigned long *entries, unsigned int nr_entries, u32 hash, depot_flags_t flags, void **prealloc) __must_hold(&pool_lock){ struct stack_record *stack = NULL; size_t record_size;
lockdep_assert_held(&pool_lock);
/* This should already be checked by public API entry points. */ if (WARN_ON_ONCE(!nr_entries)) return NULL;
/* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ if (nr_entries > CONFIG_STACKDEPOT_MAX_FRAMES) nr_entries = CONFIG_STACKDEPOT_MAX_FRAMES;
if (flags & STACK_DEPOT_FLAG_GET) { /* * Evictable entries have to allocate the max. size so they may * safely be re-used by differently sized allocations. */ record_size = depot_stack_record_size(stack, CONFIG_STACKDEPOT_MAX_FRAMES); stack = depot_pop_free(); } else { record_size = depot_stack_record_size(stack, nr_entries); }
if (!stack) { stack = depot_pop_free_pool(prealloc, record_size); if (!stack) return NULL; }
/* Save the stack trace. */ stack->hash = hash; stack->size = nr_entries; /* stack->handle is already filled in by depot_pop_free_pool(). */ memcpy(stack->entries, entries, flex_array_size(stack, entries, nr_entries));
if (flags & STACK_DEPOT_FLAG_GET) { refcount_set(&stack->count, 1); counters[DEPOT_COUNTER_REFD_ALLOCS]++; counters[DEPOT_COUNTER_REFD_INUSE]++; } else { /* Warn on attempts to switch to refcounting this entry. */ refcount_set(&stack->count, REFCOUNT_SATURATED); counters[DEPOT_COUNTER_PERSIST_COUNT]++; counters[DEPOT_COUNTER_PERSIST_BYTES] += record_size; }
/* * Let KMSAN know the stored stack record is initialized. This shall * prevent false positive reports if instrumented code accesses it. */ kmsan_unpoison_memory(stack, record_size);
return stack;}
static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) __must_not_hold(&pool_lock){ const int pools_num_cached = READ_ONCE(pools_num); union handle_parts parts = { .handle = handle }; void *pool; u32 pool_index = parts.pool_index_plus_1 - 1; size_t offset = parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack;
lockdep_assert_not_held(&pool_lock);
if (pool_index >= pools_num_cached) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", pool_index, pools_num_cached, handle); return NULL; }
/* @pool_index either valid, or user passed in corrupted value. */ pool = context_unsafe(stack_pools[pool_index]); if (WARN_ON(!pool)) return NULL;
stack = pool + offset; if (WARN_ON(!refcount_read(&stack->count))) return NULL;
return stack;}
/* Links stack into the freelist. */static void depot_free_stack(struct stack_record *stack) __must_not_hold(&pool_lock){ unsigned long flags;
lockdep_assert_not_held(&pool_lock);
raw_spin_lock_irqsave(&pool_lock, flags); printk_deferred_enter();
/* * Remove the entry from the hash list. Concurrent list traversal may * still observe the entry, but since the refcount is zero, this entry * will no longer be considered as valid. */ list_del_rcu(&stack->hash_list);
/* * Due to being used from constrained contexts such as the allocators, * NMI, or even RCU itself, stack depot cannot rely on primitives that * would sleep (such as synchronize_rcu()) or recursively call into * stack depot again (such as call_rcu()). * * Instead, get an RCU cookie, so that we can ensure this entry isn't * moved onto another list until the next grace period, and concurrent * RCU list traversal remains safe. */ stack->rcu_state = get_state_synchronize_rcu();
/* * Add the entry to the freelist tail, so that older entries are * considered first - their RCU cookie is more likely to no longer be * associated with the current grace period. */ list_add_tail(&stack->free_list, &free_stacks);
counters[DEPOT_COUNTER_FREELIST_SIZE]++; counters[DEPOT_COUNTER_REFD_FREES]++; counters[DEPOT_COUNTER_REFD_INUSE]--;
printk_deferred_exit(); raw_spin_unlock_irqrestore(&pool_lock, flags);}
/* Calculates the hash for a stack. */static inline u32 hash_stack(unsigned long *entries, unsigned int size){ return jhash2((u32 *)entries, array_size(size, sizeof(*entries)) / sizeof(u32), STACK_HASH_SEED);}
/* * Non-instrumented version of memcmp(). * Does not check the lexicographical order, only the equality. */static inlineint stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2, unsigned int n){ for ( ; n-- ; u1++, u2++) { if (*u1 != *u2) return 1; } return 0;}
/* Finds a stack in a bucket of the hash table. */static inline struct stack_record *find_stack(struct list_head *bucket, unsigned long *entries, int size, u32 hash, depot_flags_t flags){ struct stack_record *stack, *ret = NULL;
/* * Stack depot may be used from instrumentation that instruments RCU or * tracing itself; use variant that does not call into RCU and cannot be * traced. * * Note: Such use cases must take care when using refcounting to evict * unused entries, because the stack record free-then-reuse code paths * do call into RCU. */ rcu_read_lock_sched_notrace();
list_for_each_entry_rcu(stack, bucket, hash_list) { if (stack->hash != hash || stack->size != size) continue;
/* * This may race with depot_free_stack() accessing the freelist * management state unioned with @entries. The refcount is zero * in that case and the below refcount_inc_not_zero() will fail. */ if (data_race(stackdepot_memcmp(entries, stack->entries, size))) continue;
/* * Try to increment refcount. If this succeeds, the stack record * is valid and has not yet been freed. * * If STACK_DEPOT_FLAG_GET is not used, it is undefined behavior * to then call stack_depot_put() later, and we can assume that * a stack record is never placed back on the freelist. */ if ((flags & STACK_DEPOT_FLAG_GET) && !refcount_inc_not_zero(&stack->count)) continue;
ret = stack; break; }
rcu_read_unlock_sched_notrace();
return ret;}
depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, unsigned int nr_entries, gfp_t alloc_flags, depot_flags_t depot_flags){ struct list_head *bucket; struct stack_record *found = NULL; depot_stack_handle_t handle = 0; struct page *page = NULL; void *prealloc = NULL; bool allow_spin = gfpflags_allow_spinning(alloc_flags); bool can_alloc = (depot_flags & STACK_DEPOT_FLAG_CAN_ALLOC) && allow_spin; unsigned long flags; u32 hash;
if (WARN_ON(depot_flags & ~STACK_DEPOT_FLAGS_MASK)) return 0;
/* * If this stack trace is from an interrupt, including anything before * interrupt entry usually leads to unbounded stack depot growth. * * Since use of filter_irq_stacks() is a requirement to ensure stack * depot can efficiently deduplicate interrupt stacks, always * filter_irq_stacks() to simplify all callers' use of stack depot. */ nr_entries = filter_irq_stacks(entries, nr_entries);
if (unlikely(nr_entries == 0) || stack_depot_disabled) return 0;
hash = hash_stack(entries, nr_entries); bucket = &stack_table[hash & stack_hash_mask];
/* Fast path: look the stack trace up without locking. */ found = find_stack(bucket, entries, nr_entries, hash, depot_flags); if (found) goto exit;
/* * Allocate memory for a new pool if required now: * we won't be able to do that under the lock. */ if (unlikely(can_alloc && !READ_ONCE(new_pool))) { page = alloc_pages(gfp_nested_mask(alloc_flags), DEPOT_POOL_ORDER); if (page) prealloc = page_address(page); }
if (in_nmi() || !allow_spin) { /* We can never allocate in NMI context. */ WARN_ON_ONCE(can_alloc); /* Best effort; bail if we fail to take the lock. */ if (!raw_spin_trylock_irqsave(&pool_lock, flags)) goto exit; } else { raw_spin_lock_irqsave(&pool_lock, flags); } printk_deferred_enter();
/* Try to find again, to avoid concurrently inserting duplicates. */ found = find_stack(bucket, entries, nr_entries, hash, depot_flags); if (!found) { struct stack_record *new = depot_alloc_stack(entries, nr_entries, hash, depot_flags, &prealloc);
if (new) { /* * This releases the stack record into the bucket and * makes it visible to readers in find_stack(). */ list_add_rcu(&new->hash_list, bucket); found = new; } }
if (prealloc) { /* * Either stack depot already contains this stack trace, or * depot_alloc_stack() did not consume the preallocated memory. * Try to keep the preallocated memory for future. */ depot_keep_new_pool(&prealloc); }
printk_deferred_exit(); raw_spin_unlock_irqrestore(&pool_lock, flags);exit: if (prealloc) { /* Stack depot didn't use this memory, free it. */ if (!allow_spin) free_pages_nolock(virt_to_page(prealloc), DEPOT_POOL_ORDER); else free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER); } if (found) handle = found->handle.handle; return handle;}EXPORT_SYMBOL_GPL(stack_depot_save_flags);
depot_stack_handle_t stack_depot_save(unsigned long *entries, unsigned int nr_entries, gfp_t alloc_flags){ return stack_depot_save_flags(entries, nr_entries, alloc_flags, STACK_DEPOT_FLAG_CAN_ALLOC);}EXPORT_SYMBOL_GPL(stack_depot_save);
struct stack_record *__stack_depot_get_stack_record(depot_stack_handle_t handle){ if (!handle) return NULL;
return depot_fetch_stack(handle);}
unsigned int stack_depot_fetch(depot_stack_handle_t handle, unsigned long **entries){ struct stack_record *stack;
*entries = NULL; /* * Let KMSAN know *entries is initialized. This shall prevent false * positive reports if instrumented code accesses it. */ kmsan_unpoison_memory(entries, sizeof(*entries));
if (!handle || stack_depot_disabled) return 0;
stack = depot_fetch_stack(handle); /* * Should never be NULL, otherwise this is a use-after-put (or just a * corrupt handle). */ if (WARN(!stack, "corrupt handle or use after stack_depot_put()")) return 0;
*entries = stack->entries; return stack->size;}EXPORT_SYMBOL_GPL(stack_depot_fetch);
void stack_depot_put(depot_stack_handle_t handle){ struct stack_record *stack;
if (!handle || stack_depot_disabled) return;
stack = depot_fetch_stack(handle); /* * Should always be able to find the stack record, otherwise this is an * unbalanced put attempt (or corrupt handle). */ if (WARN(!stack, "corrupt handle or unbalanced stack_depot_put()")) return;
if (refcount_dec_and_test(&stack->count)) depot_free_stack(stack);}EXPORT_SYMBOL_GPL(stack_depot_put);
void stack_depot_print(depot_stack_handle_t stack){ unsigned long *entries; unsigned int nr_entries;
nr_entries = stack_depot_fetch(stack, &entries); if (nr_entries > 0) stack_trace_print(entries, nr_entries, 0);}EXPORT_SYMBOL_GPL(stack_depot_print);
int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size, int spaces){ unsigned long *entries; unsigned int nr_entries;
nr_entries = stack_depot_fetch(handle, &entries); return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries, spaces) : 0;}EXPORT_SYMBOL_GPL(stack_depot_snprint);
depot_stack_handle_t __must_check stack_depot_set_extra_bits( depot_stack_handle_t handle, unsigned int extra_bits){ union handle_parts parts = { .handle = handle };
/* Don't set extra bits on empty handles. */ if (!handle) return 0;
parts.extra = extra_bits; return parts.handle;}EXPORT_SYMBOL(stack_depot_set_extra_bits);
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle){ union handle_parts parts = { .handle = handle };
return parts.extra;}EXPORT_SYMBOL(stack_depot_get_extra_bits);
static int stats_show(struct seq_file *seq, void *v){ /* * data race ok: These are just statistics counters, and approximate * statistics are ok for debugging. */ seq_printf(seq, "pools: %d\n", data_race(pools_num)); for (int i = 0; i < DEPOT_COUNTER_COUNT; i++) seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(counters[i]));
return 0;}DEFINE_SHOW_ATTRIBUTE(stats);
static int depot_debugfs_init(void){ struct dentry *dir;
if (stack_depot_disabled) return 0;
dir = debugfs_create_dir("stackdepot", NULL); debugfs_create_file("stats", 0444, dir, NULL, &stats_fops); return 0;}late_initcall(depot_debugfs_init);