Re: [PATCH v2 2/2] alloc_tag: keep codetag iterator active between read() calls

Suren Baghdasaryan
2025-05-09T19:37:14Z

On Fri, May 9, 2025 at 11:33 AM Tim Chen <tim.c.chen@linux.intel.com> wrote:
>
> On Sat, 2025-05-10 at 01:39 +0800, David Wang wrote:
> >
> >
> > Signed-off-by: David Wang <00107082@163.com>

Acked-by: Suren Baghdasaryan <surenb@google.com>

> > ---
> > lib/alloc_tag.c | 29 ++++++++++-------------------
> > 1 file changed, 10 insertions(+), 19 deletions(-)
> >
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index 25ecc1334b67..fdd5887769a6 100644
> > --- a/lib/alloc_tag.c
> > +++ b/lib/alloc_tag.c
> > @@ -45,21 +45,16 @@ struct allocinfo_private {
> > static void *allocinfo_start(struct seq_file *m, loff_t *pos)
> > {
> > struct allocinfo_private *priv;
> > - struct codetag *ct;
> > loff_t node = *pos;
> >
> > - priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> > - m->private = priv;
> > - if (!priv)
> > - return NULL;
> > -
> > - priv->print_header = (node == 0);
> > + priv = (struct allocinfo_private *)m->private;
> > codetag_lock_module_list(alloc_tag_cttype, true);
> > - priv->iter = codetag_get_ct_iter(alloc_tag_cttype);
> > - while ((ct = codetag_next_ct(&priv->iter)) != NULL && node)
> > - node--;
> > -
> > - return ct ? priv : NULL;
> > + if (node == 0) {
> > + priv->print_header = true;
> > + priv->iter = codetag_get_ct_iter(alloc_tag_cttype);
> > + codetag_next_ct(&priv->iter);
> > + }
>
> Do you need to skip print header when *pos != 0? i.e add

Technically not needed since proc_create_seq_private() allocates
seq->private using kzalloc(), so the initial value of
priv->print_header is always false.

>
> } else {
> priv->print_header = false;
> }
>
> Tim
>
> > + return priv->iter.ct ? priv : NULL;
> > }
> >
>