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

[Dan Carpenter]

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@xxxxxxxxxx> 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