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

On Thu, Feb 17, 2022 at 6:05 AM Andrzej Hajda andrzej.hajda@intel.com wrote:

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;
  

Another iteration over a potential long list.

You can count the @skipped number in the following iteration just fine.

int skipped = 0;

•   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)
  

skipped++;

•                   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