thermal: create softlink by name for thermal_zone and cooling_device
diff mbox series

Message ID 20191015061349.141448-1-wvw@google.com
State New
Delegated to: Zhang Rui
Headers show
Series
  • thermal: create softlink by name for thermal_zone and cooling_device
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Commit Message

Wei Wang Oct. 15, 2019, 6:13 a.m. UTC
The paths thermal_zone%d and cooling_device%d are not intuitive and the
numbers are subject to change due to device tree change. This usually
leads to tree traversal in userspace code.
The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
cooling_device respectively.

Signed-off-by: Wei Wang <wvw@google.com>
---
 drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

Comments

Amit Kucheria Oct. 16, 2019, 4:50 p.m. UTC | #1
On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <wvw@google.com> wrote:
>
> The paths thermal_zone%d and cooling_device%d are not intuitive and the
> numbers are subject to change due to device tree change. This usually
> leads to tree traversal in userspace code.
> The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> cooling_device respectively.

I like this.

> Signed-off-by: Wei Wang <wvw@google.com>
> ---
>  drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index d4481cc8958f..0ff8fb1d7b0a 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -22,6 +22,7 @@
>  #include <net/netlink.h>
>  #include <net/genetlink.h>
>  #include <linux/suspend.h>
> +#include <linux/kobject.h>
>
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/thermal.h>
> @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
>
>  static atomic_t in_suspend;
>  static bool power_off_triggered;
> +static struct kobject *cdev_link_kobj;
> +static struct kobject *tz_link_kobj;
>
>  static struct thermal_governor *def_governor;
>
> @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
>         struct thermal_zone_device *pos = NULL;
>         int result;
>
> -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> +       if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
>                 return ERR_PTR(-EINVAL);

This should be a separate fix, if needed.

>         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np,
>                 return ERR_PTR(result);
>         }
>
> -       /* Add 'this' new cdev to the global cdev list */
> +       /* Add 'this' new cdev to the global cdev list and create link*/
>         mutex_lock(&thermal_list_lock);
>         list_add(&cdev->node, &thermal_cdev_list);
> +       if (!cdev_link_kobj)
> +               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> +                                               cdev->device.kobj.parent);
> +       if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> +                                               &cdev->device.kobj, cdev->type))
> +               dev_err(&cdev->device, "Failed to create cdev-by-name link\n");

Any reason not to use the following form instead? It seems easier to read.

if (!cdev_link_kobj) {
               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
                                               cdev->device.kobj.parent);
              ret = sysfs_create_link(cdev_link_kobj,
                                              &cdev->device.kobj, cdev->type))
              if (ret)
                       dev_err(&cdev->device, "Failed to create
cdev-by-name link\n");
}

>         mutex_unlock(&thermal_list_lock);
>
>         /* Update binding information for 'this' new cdev */
> @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
>                         }
>                 }
>         }
> +       if (cdev_link_kobj)
> +               sysfs_remove_link(cdev_link_kobj, cdev->type);
>
>         mutex_unlock(&thermal_list_lock);
>
> @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
>
>         mutex_lock(&thermal_list_lock);
>         list_add_tail(&tz->node, &thermal_tz_list);
> +       if (!tz_link_kobj)
> +               tz_link_kobj = kobject_create_and_add("tz-by-name",
> +                                               tz->device.kobj.parent);
> +       if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> +                                               &tz->device.kobj, tz->type))
> +               dev_err(&tz->device, "Failed to create tz-by-name link\n");

Same as above.

>         mutex_unlock(&thermal_list_lock);
>
>         /* Bind cooling devices for this zone */
> @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
>                         }
>                 }
>         }
> +       if (tz_link_kobj)
> +               sysfs_remove_link(tz_link_kobj, tz->type);
>
>         mutex_unlock(&thermal_list_lock);
>
> --
> 2.23.0.700.g56cf767bdb-goog
>
Amit Kucheria Oct. 16, 2019, 5:15 p.m. UTC | #2
On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <wvw@google.com> wrote:
> >
> > The paths thermal_zone%d and cooling_device%d are not intuitive and the
> > numbers are subject to change due to device tree change. This usually
> > leads to tree traversal in userspace code.
> > The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> > cooling_device respectively.
>
> I like this.
>
> > Signed-off-by: Wei Wang <wvw@google.com>
> > ---
> >  drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index d4481cc8958f..0ff8fb1d7b0a 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -22,6 +22,7 @@
> >  #include <net/netlink.h>
> >  #include <net/genetlink.h>
> >  #include <linux/suspend.h>
> > +#include <linux/kobject.h>
> >
> >  #define CREATE_TRACE_POINTS
> >  #include <trace/events/thermal.h>
> > @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
> >
> >  static atomic_t in_suspend;
> >  static bool power_off_triggered;
> > +static struct kobject *cdev_link_kobj;
> > +static struct kobject *tz_link_kobj;
> >
> >  static struct thermal_governor *def_governor;
> >
> > @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
> >         struct thermal_zone_device *pos = NULL;
> >         int result;
> >
> > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > +       if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
> >                 return ERR_PTR(-EINVAL);
>
> This should be a separate fix, if needed.
>
> >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np,
> >                 return ERR_PTR(result);
> >         }
> >
> > -       /* Add 'this' new cdev to the global cdev list */
> > +       /* Add 'this' new cdev to the global cdev list and create link*/
> >         mutex_lock(&thermal_list_lock);
> >         list_add(&cdev->node, &thermal_cdev_list);
> > +       if (!cdev_link_kobj)
> > +               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > +                                               cdev->device.kobj.parent);
> > +       if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> > +                                               &cdev->device.kobj, cdev->type))
> > +               dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
>
> Any reason not to use the following form instead? It seems easier to read.
>
> if (!cdev_link_kobj) {
>                cdev_link_kobj = kobject_create_and_add("cdev-by-name",
>                                                cdev->device.kobj.parent);
>               ret = sysfs_create_link(cdev_link_kobj,
>                                               &cdev->device.kobj, cdev->type))
>               if (ret)
>                        dev_err(&cdev->device, "Failed to create
> cdev-by-name link\n");
> }

I can now see why you had to do that - none of the other links would
get created after the first one.

Perhaps create the directories in the __init functions and only create
the links here?


> >         mutex_unlock(&thermal_list_lock);
> >
> >         /* Update binding information for 'this' new cdev */
> > @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
> >                         }
> >                 }
> >         }
> > +       if (cdev_link_kobj)
> > +               sysfs_remove_link(cdev_link_kobj, cdev->type);
> >
> >         mutex_unlock(&thermal_list_lock);
> >
> > @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> >
> >         mutex_lock(&thermal_list_lock);
> >         list_add_tail(&tz->node, &thermal_tz_list);
> > +       if (!tz_link_kobj)
> > +               tz_link_kobj = kobject_create_and_add("tz-by-name",
> > +                                               tz->device.kobj.parent);
> > +       if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> > +                                               &tz->device.kobj, tz->type))
> > +               dev_err(&tz->device, "Failed to create tz-by-name link\n");
>
> Same as above.
>
> >         mutex_unlock(&thermal_list_lock);
> >
> >         /* Bind cooling devices for this zone */
> > @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> >                         }
> >                 }
> >         }
> > +       if (tz_link_kobj)
> > +               sysfs_remove_link(tz_link_kobj, tz->type);
> >
> >         mutex_unlock(&thermal_list_lock);
> >
> > --
> > 2.23.0.700.g56cf767bdb-goog
> >
Wei Wang Oct. 16, 2019, 9:34 p.m. UTC | #3
On Wed, Oct 16, 2019 at 10:16 AM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria
> <amit.kucheria@verdurent.com> wrote:
> >
> > On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <wvw@google.com> wrote:
> > >
> > > The paths thermal_zone%d and cooling_device%d are not intuitive and the
> > > numbers are subject to change due to device tree change. This usually
> > > leads to tree traversal in userspace code.
> > > The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> > > cooling_device respectively.
> >
> > I like this.
> >
> > > Signed-off-by: Wei Wang <wvw@google.com>
> > > ---
> > >  drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
> > >  1 file changed, 21 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > index d4481cc8958f..0ff8fb1d7b0a 100644
> > > --- a/drivers/thermal/thermal_core.c
> > > +++ b/drivers/thermal/thermal_core.c
> > > @@ -22,6 +22,7 @@
> > >  #include <net/netlink.h>
> > >  #include <net/genetlink.h>
> > >  #include <linux/suspend.h>
> > > +#include <linux/kobject.h>
> > >
> > >  #define CREATE_TRACE_POINTS
> > >  #include <trace/events/thermal.h>
> > > @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
> > >
> > >  static atomic_t in_suspend;
> > >  static bool power_off_triggered;
> > > +static struct kobject *cdev_link_kobj;
> > > +static struct kobject *tz_link_kobj;
> > >
> > >  static struct thermal_governor *def_governor;
> > >
> > > @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > >         struct thermal_zone_device *pos = NULL;
> > >         int result;
> > >
> > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > +       if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
> > >                 return ERR_PTR(-EINVAL);
> >
> > This should be a separate fix, if needed.
Agree, but the link now requires that "" as invalid _type_.


> >
> > >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > > @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np,
> > >                 return ERR_PTR(result);
> > >         }
> > >
> > > -       /* Add 'this' new cdev to the global cdev list */
> > > +       /* Add 'this' new cdev to the global cdev list and create link*/
> > >         mutex_lock(&thermal_list_lock);
> > >         list_add(&cdev->node, &thermal_cdev_list);
> > > +       if (!cdev_link_kobj)
> > > +               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > > +                                               cdev->device.kobj.parent);
> > > +       if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> > > +                                               &cdev->device.kobj, cdev->type))
> > > +               dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
> >
> > Any reason not to use the following form instead? It seems easier to read.
> >
> > if (!cdev_link_kobj) {
> >                cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> >                                                cdev->device.kobj.parent);
> >               ret = sysfs_create_link(cdev_link_kobj,
> >                                               &cdev->device.kobj, cdev->type))
> >               if (ret)
> >                        dev_err(&cdev->device, "Failed to create
> > cdev-by-name link\n");
> > }
>
> I can now see why you had to do that - none of the other links would
> get created after the first one.
>
> Perhaps create the directories in the __init functions and only create
> the links here?
>
AFAICT, this is no such API except the private get_device_parent()
under driver/base/. Also the lazy initialization makes sense in such
case when there is no thermal device attached. Looks like the class
dir is also lazy-initialized when first device registered
https://elixir.bootlin.com/linux/v5.3.5/source/drivers/base/core.c#L1790.

>
> > >         mutex_unlock(&thermal_list_lock);
> > >
> > >         /* Update binding information for 'this' new cdev */
> > > @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
> > >                         }
> > >                 }
> > >         }
> > > +       if (cdev_link_kobj)
> > > +               sysfs_remove_link(cdev_link_kobj, cdev->type);
> > >
> > >         mutex_unlock(&thermal_list_lock);
> > >
> > > @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> > >
> > >         mutex_lock(&thermal_list_lock);
> > >         list_add_tail(&tz->node, &thermal_tz_list);
> > > +       if (!tz_link_kobj)
> > > +               tz_link_kobj = kobject_create_and_add("tz-by-name",
> > > +                                               tz->device.kobj.parent);
> > > +       if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> > > +                                               &tz->device.kobj, tz->type))
> > > +               dev_err(&tz->device, "Failed to create tz-by-name link\n");
> >
> > Same as above.
> >
> > >         mutex_unlock(&thermal_list_lock);
> > >
> > >         /* Bind cooling devices for this zone */
> > > @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> > >                         }
> > >                 }
> > >         }
> > > +       if (tz_link_kobj)
> > > +               sysfs_remove_link(tz_link_kobj, tz->type);
> > >
> > >         mutex_unlock(&thermal_list_lock);
> > >
> > > --
> > > 2.23.0.700.g56cf767bdb-goog
> > >
Amit Kucheria Nov. 11, 2019, 5:26 a.m. UTC | #4
On Thu, Oct 17, 2019 at 3:04 AM Wei Wang <wvw@google.com> wrote:
>
> On Wed, Oct 16, 2019 at 10:16 AM Amit Kucheria
> <amit.kucheria@verdurent.com> wrote:
> >
> > On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria
> > <amit.kucheria@verdurent.com> wrote:
> > >
> > > On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <wvw@google.com> wrote:
> > > >
> > > > The paths thermal_zone%d and cooling_device%d are not intuitive and the
> > > > numbers are subject to change due to device tree change. This usually
> > > > leads to tree traversal in userspace code.
> > > > The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> > > > cooling_device respectively.
> > >
> > > I like this.
> > >
> > > > Signed-off-by: Wei Wang <wvw@google.com>
> > > > ---
> > > >  drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
> > > >  1 file changed, 21 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > > index d4481cc8958f..0ff8fb1d7b0a 100644
> > > > --- a/drivers/thermal/thermal_core.c
> > > > +++ b/drivers/thermal/thermal_core.c
> > > > @@ -22,6 +22,7 @@
> > > >  #include <net/netlink.h>
> > > >  #include <net/genetlink.h>
> > > >  #include <linux/suspend.h>
> > > > +#include <linux/kobject.h>
> > > >
> > > >  #define CREATE_TRACE_POINTS
> > > >  #include <trace/events/thermal.h>
> > > > @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
> > > >
> > > >  static atomic_t in_suspend;
> > > >  static bool power_off_triggered;
> > > > +static struct kobject *cdev_link_kobj;
> > > > +static struct kobject *tz_link_kobj;
> > > >
> > > >  static struct thermal_governor *def_governor;
> > > >
> > > > @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > > >         struct thermal_zone_device *pos = NULL;
> > > >         int result;
> > > >
> > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > > +       if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
> > > >                 return ERR_PTR(-EINVAL);
> > >
> > > This should be a separate fix, if needed.
> Agree, but the link now requires that "" as invalid _type_.

I'm not sure I understand. What does this change have to do with
adding symlinks below?

> > >
> > > >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > > > @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np,
> > > >                 return ERR_PTR(result);
> > > >         }
> > > >
> > > > -       /* Add 'this' new cdev to the global cdev list */
> > > > +       /* Add 'this' new cdev to the global cdev list and create link*/
> > > >         mutex_lock(&thermal_list_lock);
> > > >         list_add(&cdev->node, &thermal_cdev_list);
> > > > +       if (!cdev_link_kobj)
> > > > +               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > > > +                                               cdev->device.kobj.parent);
> > > > +       if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> > > > +                                               &cdev->device.kobj, cdev->type))
> > > > +               dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
> > >
> > > Any reason not to use the following form instead? It seems easier to read.
> > >
> > > if (!cdev_link_kobj) {
> > >                cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > >                                                cdev->device.kobj.parent);
> > >               ret = sysfs_create_link(cdev_link_kobj,
> > >                                               &cdev->device.kobj, cdev->type))
> > >               if (ret)
> > >                        dev_err(&cdev->device, "Failed to create
> > > cdev-by-name link\n");
> > > }
> >
> > I can now see why you had to do that - none of the other links would
> > get created after the first one.
> >
> > Perhaps create the directories in the __init functions and only create
> > the links here?
> >
> AFAICT, this is no such API except the private get_device_parent()
> under driver/base/. Also the lazy initialization makes sense in such
> case when there is no thermal device attached. Looks like the class
> dir is also lazy-initialized when first device registered
> https://elixir.bootlin.com/linux/v5.3.5/source/drivers/base/core.c#L1790.

OK.

> >
> > > >         mutex_unlock(&thermal_list_lock);
> > > >
> > > >         /* Update binding information for 'this' new cdev */
> > > > @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
> > > >                         }
> > > >                 }
> > > >         }
> > > > +       if (cdev_link_kobj)
> > > > +               sysfs_remove_link(cdev_link_kobj, cdev->type);
> > > >
> > > >         mutex_unlock(&thermal_list_lock);
> > > >
> > > > @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> > > >
> > > >         mutex_lock(&thermal_list_lock);
> > > >         list_add_tail(&tz->node, &thermal_tz_list);
> > > > +       if (!tz_link_kobj)
> > > > +               tz_link_kobj = kobject_create_and_add("tz-by-name",
> > > > +                                               tz->device.kobj.parent);
> > > > +       if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> > > > +                                               &tz->device.kobj, tz->type))
> > > > +               dev_err(&tz->device, "Failed to create tz-by-name link\n");
> > >
> > > Same as above.
> > >
> > > >         mutex_unlock(&thermal_list_lock);
> > > >
> > > >         /* Bind cooling devices for this zone */
> > > > @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> > > >                         }
> > > >                 }
> > > >         }
> > > > +       if (tz_link_kobj)
> > > > +               sysfs_remove_link(tz_link_kobj, tz->type);
> > > >
> > > >         mutex_unlock(&thermal_list_lock);
> > > >
> > > > --
> > > > 2.23.0.700.g56cf767bdb-goog
> > > >
Wei Wang Nov. 11, 2019, 5:52 p.m. UTC | #5
On Sun, Nov 10, 2019 at 9:26 PM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> On Thu, Oct 17, 2019 at 3:04 AM Wei Wang <wvw@google.com> wrote:
> >
> > On Wed, Oct 16, 2019 at 10:16 AM Amit Kucheria
> > <amit.kucheria@verdurent.com> wrote:
> > >
> > > On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria
> > > <amit.kucheria@verdurent.com> wrote:
> > > >
> > > > On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <wvw@google.com> wrote:
> > > > >
> > > > > The paths thermal_zone%d and cooling_device%d are not intuitive and the
> > > > > numbers are subject to change due to device tree change. This usually
> > > > > leads to tree traversal in userspace code.
> > > > > The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> > > > > cooling_device respectively.
> > > >
> > > > I like this.
> > > >
> > > > > Signed-off-by: Wei Wang <wvw@google.com>
> > > > > ---
> > > > >  drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
> > > > >  1 file changed, 21 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > > > index d4481cc8958f..0ff8fb1d7b0a 100644
> > > > > --- a/drivers/thermal/thermal_core.c
> > > > > +++ b/drivers/thermal/thermal_core.c
> > > > > @@ -22,6 +22,7 @@
> > > > >  #include <net/netlink.h>
> > > > >  #include <net/genetlink.h>
> > > > >  #include <linux/suspend.h>
> > > > > +#include <linux/kobject.h>
> > > > >
> > > > >  #define CREATE_TRACE_POINTS
> > > > >  #include <trace/events/thermal.h>
> > > > > @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
> > > > >
> > > > >  static atomic_t in_suspend;
> > > > >  static bool power_off_triggered;
> > > > > +static struct kobject *cdev_link_kobj;
> > > > > +static struct kobject *tz_link_kobj;
> > > > >
> > > > >  static struct thermal_governor *def_governor;
> > > > >
> > > > > @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > > > >         struct thermal_zone_device *pos = NULL;
> > > > >         int result;
> > > > >
> > > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > > > +       if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
> > > > >                 return ERR_PTR(-EINVAL);
> > > >
> > > > This should be a separate fix, if needed.
> > Agree, but the link now requires that "" as invalid _type_.
>
> I'm not sure I understand. What does this change have to do with
> adding symlinks below?
>

cdev->type will be used later in sysfs_create_link and adding "" as
symlink is kind of bad practise AIUI.

thanks


> > > >
> > > > >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > > > > @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np,
> > > > >                 return ERR_PTR(result);
> > > > >         }
> > > > >
> > > > > -       /* Add 'this' new cdev to the global cdev list */
> > > > > +       /* Add 'this' new cdev to the global cdev list and create link*/
> > > > >         mutex_lock(&thermal_list_lock);
> > > > >         list_add(&cdev->node, &thermal_cdev_list);
> > > > > +       if (!cdev_link_kobj)
> > > > > +               cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > > > > +                                               cdev->device.kobj.parent);
> > > > > +       if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> > > > > +                                               &cdev->device.kobj, cdev->type))
> > > > > +               dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
> > > >
> > > > Any reason not to use the following form instead? It seems easier to read.
> > > >
> > > > if (!cdev_link_kobj) {
> > > >                cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> > > >                                                cdev->device.kobj.parent);
> > > >               ret = sysfs_create_link(cdev_link_kobj,
> > > >                                               &cdev->device.kobj, cdev->type))
> > > >               if (ret)
> > > >                        dev_err(&cdev->device, "Failed to create
> > > > cdev-by-name link\n");
> > > > }
> > >
> > > I can now see why you had to do that - none of the other links would
> > > get created after the first one.
> > >
> > > Perhaps create the directories in the __init functions and only create
> > > the links here?
> > >
> > AFAICT, this is no such API except the private get_device_parent()
> > under driver/base/. Also the lazy initialization makes sense in such
> > case when there is no thermal device attached. Looks like the class
> > dir is also lazy-initialized when first device registered
> > https://elixir.bootlin.com/linux/v5.3.5/source/drivers/base/core.c#L1790.
>
> OK.
>
> > >
> > > > >         mutex_unlock(&thermal_list_lock);
> > > > >
> > > > >         /* Update binding information for 'this' new cdev */
> > > > > @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
> > > > >                         }
> > > > >                 }
> > > > >         }
> > > > > +       if (cdev_link_kobj)
> > > > > +               sysfs_remove_link(cdev_link_kobj, cdev->type);
> > > > >
> > > > >         mutex_unlock(&thermal_list_lock);
> > > > >
> > > > > @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> > > > >
> > > > >         mutex_lock(&thermal_list_lock);
> > > > >         list_add_tail(&tz->node, &thermal_tz_list);
> > > > > +       if (!tz_link_kobj)
> > > > > +               tz_link_kobj = kobject_create_and_add("tz-by-name",
> > > > > +                                               tz->device.kobj.parent);
> > > > > +       if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> > > > > +                                               &tz->device.kobj, tz->type))
> > > > > +               dev_err(&tz->device, "Failed to create tz-by-name link\n");
> > > >
> > > > Same as above.
> > > >
> > > > >         mutex_unlock(&thermal_list_lock);
> > > > >
> > > > >         /* Bind cooling devices for this zone */
> > > > > @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> > > > >                         }
> > > > >                 }
> > > > >         }
> > > > > +       if (tz_link_kobj)
> > > > > +               sysfs_remove_link(tz_link_kobj, tz->type);
> > > > >
> > > > >         mutex_unlock(&thermal_list_lock);
> > > > >
> > > > > --
> > > > > 2.23.0.700.g56cf767bdb-goog
> > > > >

Patch
diff mbox series

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d4481cc8958f..0ff8fb1d7b0a 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -22,6 +22,7 @@ 
 #include <net/netlink.h>
 #include <net/genetlink.h>
 #include <linux/suspend.h>
+#include <linux/kobject.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/thermal.h>
@@ -46,6 +47,8 @@  static DEFINE_MUTEX(poweroff_lock);
 
 static atomic_t in_suspend;
 static bool power_off_triggered;
+static struct kobject *cdev_link_kobj;
+static struct kobject *tz_link_kobj;
 
 static struct thermal_governor *def_governor;
 
@@ -954,7 +957,7 @@  __thermal_cooling_device_register(struct device_node *np,
 	struct thermal_zone_device *pos = NULL;
 	int result;
 
-	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
+	if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
 		return ERR_PTR(-EINVAL);
 
 	if (!ops || !ops->get_max_state || !ops->get_cur_state ||
@@ -989,9 +992,15 @@  __thermal_cooling_device_register(struct device_node *np,
 		return ERR_PTR(result);
 	}
 
-	/* Add 'this' new cdev to the global cdev list */
+	/* Add 'this' new cdev to the global cdev list and create link*/
 	mutex_lock(&thermal_list_lock);
 	list_add(&cdev->node, &thermal_cdev_list);
+	if (!cdev_link_kobj)
+		cdev_link_kobj = kobject_create_and_add("cdev-by-name",
+						cdev->device.kobj.parent);
+	if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
+						&cdev->device.kobj, cdev->type))
+		dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
 	mutex_unlock(&thermal_list_lock);
 
 	/* Update binding information for 'this' new cdev */
@@ -1157,6 +1166,8 @@  void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
 			}
 		}
 	}
+	if (cdev_link_kobj)
+		sysfs_remove_link(cdev_link_kobj, cdev->type);
 
 	mutex_unlock(&thermal_list_lock);
 
@@ -1340,6 +1351,12 @@  thermal_zone_device_register(const char *type, int trips, int mask,
 
 	mutex_lock(&thermal_list_lock);
 	list_add_tail(&tz->node, &thermal_tz_list);
+	if (!tz_link_kobj)
+		tz_link_kobj = kobject_create_and_add("tz-by-name",
+						tz->device.kobj.parent);
+	if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
+						&tz->device.kobj, tz->type))
+		dev_err(&tz->device, "Failed to create tz-by-name link\n");
 	mutex_unlock(&thermal_list_lock);
 
 	/* Bind cooling devices for this zone */
@@ -1411,6 +1428,8 @@  void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 			}
 		}
 	}
+	if (tz_link_kobj)
+		sysfs_remove_link(tz_link_kobj, tz->type);
 
 	mutex_unlock(&thermal_list_lock);