Re: [PATCH v2 1/5] thermal/drivers/core: Use a char pointer for the cooling device name

[Lukasz Luba]

On 3/12/21 9:01 PM, Daniel Lezcano wrote:
> On 12/03/2021 19:49, Lukasz Luba wrote:
> > On 3/12/21 5:03 PM, Daniel Lezcano wrote:
> > > We want to have any kind of name for the cooling devices as we do no
> > > longer want to rely on auto-numbering. Let's replace the cooling
> > > device's fixed array by a char pointer to be allocated dynamically
> > > when registering the cooling device, so we don't limit the length of
> > > the name.
> > >
> > > Rework the error path at the same time as we have to rollback the
> > > allocations in case of error.
> > >
> > > Tested with a dummy device having the name:
> > >    "Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch"
> > >
> > > A village on the island of Anglesey (Wales), known to have the longest
> > > name in Europe.
> > >
> > > Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > > ---
> > >    .../ethernet/mellanox/mlxsw/core_thermal.c    |  2 +-
> > >    drivers/thermal/thermal_core.c                | 38 +++++++++++--------
> > >    include/linux/thermal.h                       |  2 +-
> > >    3 files changed, 24 insertions(+), 18 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
> > > b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
> > > index bf85ce9835d7..7447c2a73cbd 100644
> > > --- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
> > > +++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
> > > @@ -141,7 +141,7 @@ static int mlxsw_get_cooling_device_idx(struct
> > > mlxsw_thermal *thermal,
> > >        /* Allow mlxsw thermal zone binding to an external cooling
> > > device */
> > >        for (i = 0; i < ARRAY_SIZE(mlxsw_thermal_external_allowed_cdev);
> > > i++) {
> > >            if (strnstr(cdev->type, mlxsw_thermal_external_allowed_cdev[i],
> > > -                sizeof(cdev->type)))
> > > +                strlen(cdev->type)))
> > >                return 0;
> > >        }
> > >    diff --git a/drivers/thermal/thermal_core.c
> > > b/drivers/thermal/thermal_core.c
> > > index 996c038f83a4..9ef8090eb645 100644
> > > --- a/drivers/thermal/thermal_core.c
> > > +++ b/drivers/thermal/thermal_core.c
> > > @@ -960,10 +960,7 @@ __thermal_cooling_device_register(struct
> > > device_node *np,
> > >    {
> > >        struct thermal_cooling_device *cdev;
> > >        struct thermal_zone_device *pos = NULL;
> > > -    int result;
> > > -
> > > -    if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > -        return ERR_PTR(-EINVAL);
> > > +    int ret;
> > >          if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > >            !ops->set_cur_state)
> > > @@ -973,14 +970,17 @@ __thermal_cooling_device_register(struct
> > > device_node *np,
> > >        if (!cdev)
> > >            return ERR_PTR(-ENOMEM);
> > >    -    result = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
> > > -    if (result < 0) {
> > > -        kfree(cdev);
> > > -        return ERR_PTR(result);
> > > +    ret = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
> > > +    if (ret < 0)
> > > +        goto out_kfree_cdev;
> > > +    cdev->id = ret;
> > > +
> > > +    cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
> > > +    if (!cdev->type) {
> > > +        ret = -ENOMEM;
> >
> > Since we haven't called the device_register() yet, I would call here:
> > kfree(cdev);
> > and then jump
>
> I'm not sure to understand, we have to remove the ida, no ?

Yes, we have to remove 'ida' and you jump to that label:
goto out_ida_remove;
but under that label, there is no 'put_device()'.
We could have here, before the 'goto', a simple kfree, which
should be safe, since we haven't called the device_register() yet.
Something like:

--------8<------------------------------
cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
if (!cdev->type) {
	ret = -ENOMEM;
	kfree(cdev);
	goto out_ida_remove;
}

-------->8------------------------------


> > Other than that, LGTM
> >
> > Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>
> >
> > Regards,
> > Lukasz