diff options
| -rw-r--r-- | include/linux/stackdepot.h | 14 | ||||
| -rw-r--r-- | lib/stackdepot.c | 37 |
2 files changed, 50 insertions, 1 deletions
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index 611716702d73..a6796f178913 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -97,6 +97,8 @@ static inline int stack_depot_early_init(void) { return 0; } * * If STACK_DEPOT_FLAG_GET is set in @depot_flags, stack depot will increment * the refcount on the saved stack trace if it already exists in stack depot. + * Users of this flag must also call stack_depot_put() when keeping the stack + * trace is no longer required to avoid overflowing the refcount. * * If the provided stack trace comes from the interrupt context, only the part * up to the interrupt entry is saved. @@ -163,6 +165,18 @@ int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size, int spaces); /** + * stack_depot_put - Drop a reference to a stack trace from stack depot + * + * @handle: Stack depot handle returned from stack_depot_save() + * + * The stack trace is evicted from stack depot once all references to it have + * been dropped (once the number of stack_depot_evict() calls matches the + * number of stack_depot_save_flags() calls with STACK_DEPOT_FLAG_GET set for + * this stack trace). + */ +void stack_depot_put(depot_stack_handle_t handle); + +/** * stack_depot_set_extra_bits - Set extra bits in a stack depot handle * * @handle: Stack depot handle returned from stack_depot_save() diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 911dee11bf39..c1b31160f4b4 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -394,7 +394,7 @@ static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) size_t offset = parts.offset << DEPOT_STACK_ALIGN; struct stack_record *stack; - lockdep_assert_held_read(&pool_rwlock); + lockdep_assert_held(&pool_rwlock); if (parts.pool_index > pools_num) { WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", @@ -410,6 +410,14 @@ static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle) return stack; } +/* Links stack into the freelist. */ +static void depot_free_stack(struct stack_record *stack) +{ + lockdep_assert_held_write(&pool_rwlock); + + list_add(&stack->list, &free_stacks); +} + /* Calculates the hash for a stack. */ static inline u32 hash_stack(unsigned long *entries, unsigned int size) { @@ -592,6 +600,33 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, } EXPORT_SYMBOL_GPL(stack_depot_fetch); +void stack_depot_put(depot_stack_handle_t handle) +{ + struct stack_record *stack; + unsigned long flags; + + if (!handle || stack_depot_disabled) + return; + + write_lock_irqsave(&pool_rwlock, flags); + + stack = depot_fetch_stack(handle); + if (WARN_ON(!stack)) + goto out; + + if (refcount_dec_and_test(&stack->count)) { + /* Unlink stack from the hash table. */ + list_del(&stack->list); + + /* Free stack. */ + depot_free_stack(stack); + } + +out: + write_unlock_irqrestore(&pool_rwlock, flags); +} +EXPORT_SYMBOL_GPL(stack_depot_put); + void stack_depot_print(depot_stack_handle_t stack) { unsigned long *entries; |