Re: [PATCH v2 2/2] pinctrl: pinmux: Add pinmux-select debugfs file

Dan Carpenter
2021-02-10T19:07:24Z

On Wed, Feb 10, 2021 at 07:39:16PM +0100, Geert Uytterhoeven wrote:
> Hi Dan,
>
> On Wed, Feb 10, 2021 at 7:21 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 694 buf = devm_kzalloc(pctldev->dev, PINMUX_MAX_NAME * 2, GFP_KERNEL);
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 695 if (!buf)
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 696 return -ENOMEM;
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 697
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 698 fname = devm_kzalloc(pctldev->dev, PINMUX_MAX_NAME, GFP_KERNEL);
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 699 if (!fname) {
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 700 ret = -ENOMEM;
> > 99b2f99aa41aa7 Drew Fustini 2021-02-09 701 goto free_buf;
> >
> > The gotos are out of order. They should be in mirror/reverse order of
> > the allocations:
> >
> > free_gmane:
> > devm_kfree(pctldev->dev, gname);
> > free_fname:
> > devm_kfree(pctldev->dev, fname);
> > free_buf:
> > devm_kfree(pctldev->dev, buf);
> >
> > But also why do we need to use devm_kfree() at all? I thought the whole
> > point of devm_ functions was that they are garbage collected
> > automatically for you. Can we not just delete all error handling and
> > return -ENOMEM here?
>
> No, because the lifetime of the objects allocated here does not match the
> lifetime of dev. If they're not freed here, they will only be freed when the
> device is unbound. As the user can access the sysfs files at will, he can
> OOM the system.
>

Then why not use vanilla kmalloc()?

regards,
dan carpenter