[PATCH 1/9] lib/ref_tracker: add unlocked leak print helper

Andrzej Hajda
2022-02-17T14:05:10Z

To have reliable detection of leaks, caller must be able to check under the same
lock both: tracked counter and the leaks. dir.lock is natural candidate for such
lock and unlocked print helper can be called with this lock taken.
As a bonus we can reuse this helper in ref_tracker_dir_exit.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Chris Wilson <chris.p.wilson@intel.com>
---
include/linux/ref_tracker.h | 8 +++++
lib/ref_tracker.c | 66 +++++++++++++++++++++----------------
2 files changed, 46 insertions(+), 28 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 60f3453be23e6..b9c968a716483 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -32,6 +32,9 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,

void ref_tracker_dir_exit(struct ref_tracker_dir *dir);

+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+ unsigned int display_limit);
+
void ref_tracker_dir_print(struct ref_tracker_dir *dir,
unsigned int display_limit);

@@ -52,6 +55,11 @@ 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 void ref_tracker_dir_print(struct ref_tracker_dir *dir,
unsigned int display_limit)
{
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index a6789c0c626b0..1b0c6d645d64a 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -14,6 +14,38 @@ struct ref_tracker {
depot_stack_handle_t free_stack_handle;
};

+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+ unsigned int display_limit)
+{
+ struct ref_tracker *tracker;
+ unsigned int i = 0;
+
+ lockdep_assert_held(&dir->lock);
+
+ 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;
+ }
+ }
+}
+EXPORT_SYMBOL(__ref_tracker_dir_print);
+
+void ref_tracker_dir_print(struct ref_tracker_dir *dir,
+ unsigned int display_limit)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dir->lock, flags);
+ __ref_tracker_dir_print(dir, display_limit);
+ spin_unlock_irqrestore(&dir->lock, flags);
+}
+EXPORT_SYMBOL(ref_tracker_dir_print);
+
void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
{
struct ref_tracker *tracker, *n;
@@ -26,13 +58,13 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
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);
+ if (!list_empty(&dir->list)) {
+ __ref_tracker_dir_print(dir, 16);
leak = true;
- list_del(&tracker->head);
- kfree(tracker);
+ list_for_each_entry_safe(tracker, n, &dir->list, head) {
+ list_del(&tracker->head);
+ kfree(tracker);
+ }
}
spin_unlock_irqrestore(&dir->lock, flags);
WARN_ON_ONCE(leak);
@@ -40,28 +72,6 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
}
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)
--
2.25.1