diff options
| -rw-r--r-- | include/linux/ref_tracker.h | 73 | ||||
| -rw-r--r-- | lib/Kconfig | 5 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/ref_tracker.c | 140 |
4 files changed, 220 insertions, 0 deletions
diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h new file mode 100644 index 000000000000..c11c9db5825c --- /dev/null +++ b/include/linux/ref_tracker.h @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#ifndef _LINUX_REF_TRACKER_H +#define _LINUX_REF_TRACKER_H +#include <linux/refcount.h> +#include <linux/types.h> +#include <linux/spinlock.h> + +struct ref_tracker; + +struct ref_tracker_dir { +#ifdef CONFIG_REF_TRACKER + spinlock_t lock; + unsigned int quarantine_avail; + refcount_t untracked; + struct list_head list; /* List of active trackers */ + struct list_head quarantine; /* List of dead trackers */ +#endif +}; + +#ifdef CONFIG_REF_TRACKER +static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir, + unsigned int quarantine_count) +{ + INIT_LIST_HEAD(&dir->list); + INIT_LIST_HEAD(&dir->quarantine); + spin_lock_init(&dir->lock); + dir->quarantine_avail = quarantine_count; + refcount_set(&dir->untracked, 1); +} + +void ref_tracker_dir_exit(struct ref_tracker_dir *dir); + +void ref_tracker_dir_print(struct ref_tracker_dir *dir, + unsigned int display_limit); + +int ref_tracker_alloc(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp, gfp_t gfp); + +int ref_tracker_free(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp); + +#else /* CONFIG_REF_TRACKER */ + +static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir, + unsigned int quarantine_count) +{ +} + +static inline void ref_tracker_dir_exit(struct ref_tracker_dir *dir) +{ +} + +static inline void ref_tracker_dir_print(struct ref_tracker_dir *dir, + unsigned int display_limit) +{ +} + +static inline int ref_tracker_alloc(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp, + gfp_t gfp) +{ + return 0; +} + +static inline int ref_tracker_free(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp) +{ + return 0; +} + +#endif + +#endif /* _LINUX_REF_TRACKER_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 5e7165e6a346..655b0e43f260 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -680,6 +680,11 @@ config STACK_HASH_ORDER Select the hash size as a power of 2 for the stackdepot hash table. Choose a lower value to reduce the memory impact. +config REF_TRACKER + bool + depends on STACKTRACE_SUPPORT + select STACKDEPOT + config SBITMAP bool diff --git a/lib/Makefile b/lib/Makefile index 364c23f15578..c1fd9243ddb9 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -270,6 +270,8 @@ obj-$(CONFIG_STACKDEPOT) += stackdepot.o KASAN_SANITIZE_stackdepot.o := n KCOV_INSTRUMENT_stackdepot.o := n +obj-$(CONFIG_REF_TRACKER) += ref_tracker.o + libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o \ fdt_empty_tree.o fdt_addresses.o $(foreach file, $(libfdt_files), \ diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c new file mode 100644 index 000000000000..0ae2e66dcf0f --- /dev/null +++ b/lib/ref_tracker.c @@ -0,0 +1,140 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include <linux/export.h> +#include <linux/ref_tracker.h> +#include <linux/slab.h> +#include <linux/stacktrace.h> +#include <linux/stackdepot.h> + +#define REF_TRACKER_STACK_ENTRIES 16 + +struct ref_tracker { + struct list_head head; /* anchor into dir->list or dir->quarantine */ + bool dead; + depot_stack_handle_t alloc_stack_handle; + depot_stack_handle_t free_stack_handle; +}; + +void ref_tracker_dir_exit(struct ref_tracker_dir *dir) +{ + struct ref_tracker *tracker, *n; + unsigned long flags; + bool leak = false; + + spin_lock_irqsave(&dir->lock, flags); + list_for_each_entry_safe(tracker, n, &dir->quarantine, head) { + list_del(&tracker->head); + kfree(tracker); + dir->quarantine_avail++; + } + list_for_each_entry_safe(tracker, n, &dir->list, head) { + pr_err("leaked reference.\n"); + if (tracker->alloc_stack_handle) + stack_depot_print(tracker->alloc_stack_handle); + leak = true; + list_del(&tracker->head); + kfree(tracker); + } + spin_unlock_irqrestore(&dir->lock, flags); + WARN_ON_ONCE(leak); + WARN_ON_ONCE(refcount_read(&dir->untracked) != 1); +} +EXPORT_SYMBOL(ref_tracker_dir_exit); + +void ref_tracker_dir_print(struct ref_tracker_dir *dir, + unsigned int display_limit) +{ + struct ref_tracker *tracker; + unsigned long flags; + unsigned int i = 0; + + spin_lock_irqsave(&dir->lock, flags); + list_for_each_entry(tracker, &dir->list, head) { + if (i < display_limit) { + pr_err("leaked reference.\n"); + if (tracker->alloc_stack_handle) + stack_depot_print(tracker->alloc_stack_handle); + i++; + } else { + break; + } + } + spin_unlock_irqrestore(&dir->lock, flags); +} +EXPORT_SYMBOL(ref_tracker_dir_print); + +int ref_tracker_alloc(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp, + gfp_t gfp) +{ + unsigned long entries[REF_TRACKER_STACK_ENTRIES]; + struct ref_tracker *tracker; + unsigned int nr_entries; + unsigned long flags; + + *trackerp = tracker = kzalloc(sizeof(*tracker), gfp | __GFP_NOFAIL); + if (unlikely(!tracker)) { + pr_err_once("memory allocation failure, unreliable refcount tracker.\n"); + refcount_inc(&dir->untracked); + return -ENOMEM; + } + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1); + nr_entries = filter_irq_stacks(entries, nr_entries); + tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp); + + spin_lock_irqsave(&dir->lock, flags); + list_add(&tracker->head, &dir->list); + spin_unlock_irqrestore(&dir->lock, flags); + return 0; +} +EXPORT_SYMBOL_GPL(ref_tracker_alloc); + +int ref_tracker_free(struct ref_tracker_dir *dir, + struct ref_tracker **trackerp) +{ + unsigned long entries[REF_TRACKER_STACK_ENTRIES]; + struct ref_tracker *tracker = *trackerp; + depot_stack_handle_t stack_handle; + unsigned int nr_entries; + unsigned long flags; + + if (!tracker) { + refcount_dec(&dir->untracked); + return -EEXIST; + } + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1); + nr_entries = filter_irq_stacks(entries, nr_entries); + stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC); + + spin_lock_irqsave(&dir->lock, flags); + if (tracker->dead) { + pr_err("reference already released.\n"); + if (tracker->alloc_stack_handle) { + pr_err("allocated in:\n"); + stack_depot_print(tracker->alloc_stack_handle); + } + if (tracker->free_stack_handle) { + pr_err("freed in:\n"); + stack_depot_print(tracker->free_stack_handle); + } + spin_unlock_irqrestore(&dir->lock, flags); + WARN_ON_ONCE(1); + return -EINVAL; + } + tracker->dead = true; + + tracker->free_stack_handle = stack_handle; + + list_move_tail(&tracker->head, &dir->quarantine); + if (!dir->quarantine_avail) { + tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head); + list_del(&tracker->head); + } else { + dir->quarantine_avail--; + tracker = NULL; + } + spin_unlock_irqrestore(&dir->lock, flags); + + kfree(tracker); + return 0; +} +EXPORT_SYMBOL_GPL(ref_tracker_free); |