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-rw-r--r--include/linux/ref_tracker.h73
-rw-r--r--lib/Kconfig5
-rw-r--r--lib/Makefile2
-rw-r--r--lib/ref_tracker.c140
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);
generated by cgit v1.2.3-70-g09d2 (git 2.47.1) at 2024-12-24 20:02:29 +0000