linux-kernel - Re: [Intel-gfx] [PATCH v4 02/10] lib/ref_tracker: __ref_tracker_dir

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Message-ID: <ZBeWnKmLiGOOMOiG@ashyti-mobl2.lan>
Date:   Mon, 20 Mar 2023 00:11:24 +0100
From:   Andi Shyti <andi.shyti@...ux.intel.com>
To:     Andrzej Hajda <andrzej.hajda@...el.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, netdev@...r.kernel.org,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Eric Dumazet <edumazet@...gle.com>,
        Chris Wilson <chris.p.wilson@...el.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [Intel-gfx] [PATCH v4 02/10] lib/ref_tracker:
 __ref_tracker_dir_print improve printing

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.hajda@...el.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?

> +		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?

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