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

Andrzej Hajda
2022-02-18T10:11:39Z

On 17.02.2022 16:38, Eric Dumazet wrote:
> 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.

Skipped is already in 'count', but you are right with double looping> I
can count total in the same loop,
just forgot to merge loops during code evolution.
Will be fixed.

Regards
Andrzej

> 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
>>