Re: [Intel-gfx] [PATCH v4 02/10] lib/ref_tracker: __ref_tracker_dir_print improve printing

[Andrzej Hajda]

On 20.03.2023 00:11, Andi Shyti wrote:
Hi Andrzej,
looks good, few comments below,

On Mon, Mar 06, 2023 at 05:31:58PM +0100, Andrzej Hajda wrote:
To improve readability of ref_tracker printing following changes
have been performed:
- reports are printed per stack_handle - log is more compact,
- 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.

nit: I think you can do better with the log :)

Signed-off-by: Andrzej Hajda <andrzej.ha...@intel.com>
---
  include/linux/ref_tracker.h | 15 ++++++--
  lib/ref_tracker.c           | 90 +++++++++++++++++++++++++++++++++++++++------
  2 files changed, 91 insertions(+), 14 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 3e9e9df2a41f5f..a2cf1f6309adb2 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -17,12 +17,19 @@ struct ref_tracker_dir {
        bool                    dead;
        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

I thought only Linus was allowed to use '//' :)

+#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)

[...]

+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+                          unsigned int display_limit)
+{
+       struct ref_tracker_dir_stats *stats;
+       unsigned int i = 0, skipped;
+       depot_stack_handle_t stack;
+       char *sbuf;
+
+       lockdep_assert_held(&dir->lock);
+
+       if (list_empty(&dir->list))
+               return;
+
+       stats = ref_tracker_get_stats(dir, display_limit);
+       if (IS_ERR(stats)) {
+               pr_err("%s@%pK: couldn't get stats, error %pe\n",
+                      dir->name, dir, stats);
+               return;
        }
+
+       sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
+
+       for (i = 0, skipped = stats->total; i < stats->count; ++i) {
+               stack = stats->stacks[i].stack_handle;
+               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,
+                      stats->stacks[i].count, stats->total, sbuf);

what if sbuf is NULL?

Then "(NULL)" will be printed, I suspect it will occur only on very rare 
occasions.


+               skipped -= stats->stacks[i].count;
+       }
+
+       if (skipped)

is skipped used to double check whether stats->count is equal to
all the stacks[].conunts? What are the cases when skipped is > 0?

There is display_limit parameter, so the function prints up to 
display_limit reports, and brief summary on remaining ones - the skipped 
ones.

Regards
Andrzej



Andi

+               pr_err("%s@%pK skipped reports about %d/%d users.\n",
+                      dir->name, dir, skipped, stats->total);
+
+       kfree(sbuf);
+
+       kfree(stats);
  }
  EXPORT_SYMBOL(__ref_tracker_dir_print);
  

--
2.34.1