Re: [Intel-gfx] [PATCH v4 03/10] lib/ref_tracker: add printing to memory buffer

[Andrzej Hajda]

On 20.03.2023 00:18, Andi Shyti wrote:
> Hi Andrzej,
>
> This looks also good, just few questions.
>
> On Mon, Mar 06, 2023 at 05:31:59PM +0100, Andrzej Hajda wrote:
> > In case one wants to show stats via debugfs.
>
> shall I say it? I'll say it... you can do better with the log
> here. It's not a typo fix :)
>
> > Signed-off-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
>
> [...]
>
> > +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
> > +			   unsigned int display_limit)
> > +{
> > +	struct ostream os = {};
> > +
> > +	__ref_tracker_dir_pr_ostream(dir, display_limit, &os);
> > +}
> >   EXPORT_SYMBOL(__ref_tracker_dir_print);
> >   
> >   void ref_tracker_dir_print(struct ref_tracker_dir *dir,
> > @@ -114,6 +141,19 @@ void ref_tracker_dir_print(struct ref_tracker_dir *dir,
> >   }
> >   EXPORT_SYMBOL(ref_tracker_dir_print);
> >   
> > +int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)
>
> nit: snprintf is normally referred to its variable parameter
> counterpart... I would choose a different name... how about
> ref_tracker_dir_fetch_print()?


Hmm, original ref_tracker_dir_print prints the stats to dmesg,
ref_tracker_dir_snprint prints to memory buffer, like:
- stack_depot_print and stack_depot_snprint,
- stack_trace_print and stack_trace_snprint.


> > +{
> > +	struct ostream os = { .buf = buf, .size = size };
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&dir->lock, flags);
> > +	__ref_tracker_dir_pr_ostream(dir, 16, &os);
> > +	spin_unlock_irqrestore(&dir->lock, flags);
>
> What are you trying to protect with this spinlock? what if
> the caller has already locked here? do we need a _locked()
> version?

spinlock is to serialize access to dir,
at the moment _locked version is not necessary, but it can be easily 
added if needed.

Regards
Andrzej


> Thanks,
> Andi
>
> > +	return os.used;
> > +}
> > +EXPORT_SYMBOL(ref_tracker_dir_snprint);
> > +
> >   void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
> >   {
> >   	struct ref_tracker *tracker, *n;
> >
> > --
> > 2.34.1