[PATCH 3/9] lib/ref_tracker: __ref_tracker_dir_print improve printing

Andrzej Hajda
2022-02-17T14:05:18Z

To improve readibility of ref_tracker printing following changes
have been performed:
- added display name for ref_tracker_dir,
- stack trace is printed indented, in the same printk call,
- total number of references is printed every time,
- print info about dropped references.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Chris Wilson <chris.p.wilson@intel.com>
---
include/linux/ref_tracker.h | 15 ++++++++++++---
lib/ref_tracker.c | 28 ++++++++++++++++++++++------
2 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index b9c968a716483..090230e5b485d 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -15,18 +15,26 @@ struct ref_tracker_dir {
refcount_t untracked;
struct list_head list; /* List of active trackers */
struct list_head quarantine; /* List of dead trackers */
+ char name[32];
#endif
};

#ifdef CONFIG_REF_TRACKER
-static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
- unsigned int quarantine_count)
+
+// Temporary allow two and three arguments, until consumers are converted
+#define ref_tracker_dir_init(_d, _q, args...) _ref_tracker_dir_init(_d, _q, ##args, #_d)
+#define _ref_tracker_dir_init(_d, _q, _n, ...) __ref_tracker_dir_init(_d, _q, _n)
+
+static inline void __ref_tracker_dir_init(struct ref_tracker_dir *dir,
+ unsigned int quarantine_count,
+ const char *name)
{
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);
+ strlcpy(dir->name, name, sizeof(dir->name));
stack_depot_init();
}

@@ -47,7 +55,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
#else /* CONFIG_REF_TRACKER */

static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
- unsigned int quarantine_count)
+ unsigned int quarantine_count,
+ ...)
{
}

diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 0e9c7d2828ccb..943cff08110e3 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -1,4 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-or-later
+
+#define pr_fmt(fmt) "ref_tracker: " fmt
+
#include <linux/export.h>
#include <linux/list_sort.h>
#include <linux/ref_tracker.h>
@@ -7,6 +10,7 @@
#include <linux/stackdepot.h>

#define REF_TRACKER_STACK_ENTRIES 16
+#define STACK_BUF_SIZE 1024

struct ref_tracker {
struct list_head head; /* anchor into dir->list or dir->quarantine */
@@ -26,31 +30,43 @@ static int ref_tracker_cmp(void *priv, const struct list_head *a, const struct l
void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
unsigned int display_limit)
{
- unsigned int i = 0, count = 0;
+ unsigned int i = 0, count = 0, total = 0;
struct ref_tracker *tracker;
depot_stack_handle_t stack;
+ char *sbuf;

lockdep_assert_held(&dir->lock);

if (list_empty(&dir->list))
return;

+ sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT);
+
+ list_for_each_entry(tracker, &dir->list, head)
+ ++total;
+
list_sort(NULL, &dir->list, ref_tracker_cmp);

list_for_each_entry(tracker, &dir->list, head) {
- if (i++ >= display_limit)
- break;
if (!count++)
stack = tracker->alloc_stack_handle;
if (stack == tracker->alloc_stack_handle &&
!list_is_last(&tracker->head, &dir->list))
continue;
+ if (i++ >= display_limit)
+ continue;

- pr_err("leaked %d references.\n", count);
- if (stack)
- stack_depot_print(stack);
+ if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
+ sbuf[0] = 0;
+ pr_err("%s@%pK has %d/%d users at\n%s\n",
+ dir->name, dir, count, total, sbuf);
count = 0;
}
+ if (i > display_limit)
+ pr_err("%s@%pK skipped %d/%d reports with %d unique stacks.\n",
+ dir->name, dir, count, total, i - display_limit);
+
+ kfree(sbuf);
}
EXPORT_SYMBOL(__ref_tracker_dir_print);

--
2.25.1