[PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Wei Wang]

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(-)

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);
 
-- 
2.23.0.700.g56cf767bdb-goog

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Amit Kucheria]

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
>

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Amit Kucheria]

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
> >

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Wei Wang]

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
> > >

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Amit Kucheria]

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
> > > >

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Wei Wang]

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
> > > > >

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Amit Kucheria]

On Mon, Nov 11, 2019 at 11:22 PM Wei Wang <wvw@google.com> wrote:
>
> 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.
>

Perhaps I'm being dense here, in which case my apologies.

But what stops us from splitting the patch into two?
1. Make type == "" as invalid by using your change above and fixing up
the strlcpy(cdev->type....) further down.
2. Create the actual symlinks in a separate patch.

Regards,
Amit

> > > > >
> > > > > >         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 v2 0/2] thermal: introduce by-name softlink

[Wei Wang]

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.

Changes since v1 [1]:
 * Split cooling device registration into a seperate patch

[1]: v1: https://lore.kernel.org/patchwork/patch/1139450/

Wei Wang (2):
  thermal: fix and clean up tz and cdev registration
  thermal: create softlink by name for thermal_zone and cooling_device

 drivers/thermal/thermal_core.c | 37 +++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

-- 
2.24.0.393.g34dc348eaf-goog

[PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Wei Wang]

Make cooling device registration behavior consistent with
thermal zone. This patch also cleans up a unnecessary
nullptr check.

Signed-off-by: Wei Wang <wvw@google.com>
---
 drivers/thermal/thermal_core.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d4481cc8958f..64fbb59c2f44 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct device_node *np,
 	struct thermal_zone_device *pos = NULL;
 	int result;
 
-	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
-		return ERR_PTR(-EINVAL);
+	if (!type || !type[0]) {
+	    pr_err("Error: No cooling device type defined\n");
+	    return ERR_PTR(-EINVAL);
+	}
+
+	if (strlen(type) >= THERMAL_NAME_LENGTH) {
+	    pr_err("Error: Cooling device name (%s) too long, "
+		   "should be under %d chars\n", type, THERMAL_NAME_LENGTH);
+	    return ERR_PTR(-EINVAL);
+	}
 
 	if (!ops || !ops->get_max_state || !ops->get_cur_state ||
 	    !ops->set_cur_state)
@@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct device_node *np,
 	}
 
 	cdev->id = result;
-	strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
+	strlcpy(cdev->type, type, sizeof(cdev->type));
 	mutex_init(&cdev->lock);
 	INIT_LIST_HEAD(&cdev->thermal_instances);
 	cdev->np = np;
@@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char *type, int trips, int mask,
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
+	if (strlen(type) >= THERMAL_NAME_LENGTH) {
 		pr_err("Error: Thermal zone name (%s) too long, should be under %d chars\n",
 		       type, THERMAL_NAME_LENGTH);
 		return ERR_PTR(-EINVAL);
-- 
2.24.0.393.g34dc348eaf-goog

[PATCH v2 2/2] thermal: create softlink by name for thermal_zone and cooling_device

[Wei Wang]

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 | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 64fbb59c2f44..4f55e3f16265 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;
 
@@ -997,9 +1000,15 @@ __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 */
@@ -1165,6 +1174,8 @@ 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);
 
@@ -1348,6 +1359,12 @@ 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 */
@@ -1419,6 +1436,8 @@ 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);
 
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device

[Wei Wang]

On Wed, Dec 4, 2019 at 4:45 AM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> On Mon, Nov 11, 2019 at 11:22 PM Wei Wang <wvw@google.com> wrote:
> >
> > 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.
> >
>
> Perhaps I'm being dense here, in which case my apologies.
>
> But what stops us from splitting the patch into two?
> 1. Make type == "" as invalid by using your change above and fixing up
> the strlcpy(cdev->type....) further down.
> 2. Create the actual symlinks in a separate patch.
>
> Regards,
> Amit
>
Updated with v2, 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
> > > > > > >

Re: [PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Amit Kucheria]

Hi Wei,

On Thu, Dec 5, 2019 at 3:26 AM Wei Wang <wvw@google.com> wrote:
>
> Make cooling device registration behavior consistent with

Consistent how? Please add details.

> thermal zone. This patch also cleans up a unnecessary
> nullptr check.
>
> Signed-off-by: Wei Wang <wvw@google.com>
> ---
>  drivers/thermal/thermal_core.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index d4481cc8958f..64fbb59c2f44 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct device_node *np,
>         struct thermal_zone_device *pos = NULL;
>         int result;
>
> -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> -               return ERR_PTR(-EINVAL);
> +       if (!type || !type[0]) {
> +           pr_err("Error: No cooling device type defined\n");
> +           return ERR_PTR(-EINVAL);
> +       }
> +
> +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> +           pr_err("Error: Cooling device name (%s) too long, "
> +                  "should be under %d chars\n", type, THERMAL_NAME_LENGTH);

Consider fitting into a single greppable string as "Error: Cooling
device name over %d chars: %s\n"

> +           return ERR_PTR(-EINVAL);
> +       }
>
>         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
>             !ops->set_cur_state)
> @@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct device_node *np,
>         }
>
>         cdev->id = result;
> -       strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
> +       strlcpy(cdev->type, type, sizeof(cdev->type));
>         mutex_init(&cdev->lock);
>         INIT_LIST_HEAD(&cdev->thermal_instances);
>         cdev->np = np;
> @@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char *type, int trips, int mask,
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
> +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
>                 pr_err("Error: Thermal zone name (%s) too long, should be under %d chars\n",
>                        type, THERMAL_NAME_LENGTH);
>                 return ERR_PTR(-EINVAL);
> --
> 2.24.0.393.g34dc348eaf-goog
>

Re: [PATCH v2 2/2] thermal: create softlink by name for thermal_zone and cooling_device

[Amit Kucheria]

On Thu, Dec 5, 2019 at 3:26 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.
>
> Signed-off-by: Wei Wang <wvw@google.com>

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>

> ---
>  drivers/thermal/thermal_core.c | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 64fbb59c2f44..4f55e3f16265 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;
>
> @@ -997,9 +1000,15 @@ __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 */
> @@ -1165,6 +1174,8 @@ 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);
>
> @@ -1348,6 +1359,12 @@ 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 */
> @@ -1419,6 +1436,8 @@ 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);
>
> --
> 2.24.0.393.g34dc348eaf-goog
>

Re: [PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Wei Wang]

On Wed, Dec 4, 2019 at 8:13 PM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> Hi Wei,
>
> On Thu, Dec 5, 2019 at 3:26 AM Wei Wang <wvw@google.com> wrote:
> >
> > Make cooling device registration behavior consistent with
>
> Consistent how? Please add details.
>
Consistent with
https://lore.kernel.org/linux-pm/1478581767-7009-2-git-send-email-edubezval@gmail.com/

will include aboce in next version.

> > thermal zone. This patch also cleans up a unnecessary
> > nullptr check.
> >
> > Signed-off-by: Wei Wang <wvw@google.com>
> > ---
> >  drivers/thermal/thermal_core.c | 16 ++++++++++++----
> >  1 file changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index d4481cc8958f..64fbb59c2f44 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct device_node *np,
> >         struct thermal_zone_device *pos = NULL;
> >         int result;
> >
> > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > -               return ERR_PTR(-EINVAL);
> > +       if (!type || !type[0]) {
> > +           pr_err("Error: No cooling device type defined\n");
> > +           return ERR_PTR(-EINVAL);
> > +       }
> > +
> > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > +           pr_err("Error: Cooling device name (%s) too long, "
> > +                  "should be under %d chars\n", type, THERMAL_NAME_LENGTH);
>
> Consider fitting into a single greppable string as "Error: Cooling
> device name over %d chars: %s\n"
>
Was intentionally keep it the same as this
https://lore.kernel.org/linux-pm/31a29628894a14e716fff113fd9ce945fe649c05.1562876950.git.amit.kucheria@linaro.org/
Will make it shorter in both places next verion

> > +           return ERR_PTR(-EINVAL);
> > +       }
> >
> >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> >             !ops->set_cur_state)
> > @@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct device_node *np,
> >         }
> >
> >         cdev->id = result;
> > -       strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
> > +       strlcpy(cdev->type, type, sizeof(cdev->type));
> >         mutex_init(&cdev->lock);
> >         INIT_LIST_HEAD(&cdev->thermal_instances);
> >         cdev->np = np;
> > @@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> >                 return ERR_PTR(-EINVAL);
> >         }
> >
> > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
> > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> >                 pr_err("Error: Thermal zone name (%s) too long, should be under %d chars\n",
> >                        type, THERMAL_NAME_LENGTH);
> >                 return ERR_PTR(-EINVAL);
> > --
> > 2.24.0.393.g34dc348eaf-goog
> >

Re: [PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Amit Kucheria]

On Thu, Dec 5, 2019 at 11:44 AM Wei Wang <wvw@google.com> wrote:
>
> On Wed, Dec 4, 2019 at 8:13 PM Amit Kucheria
> <amit.kucheria@verdurent.com> wrote:
> >
> > Hi Wei,
> >
> > On Thu, Dec 5, 2019 at 3:26 AM Wei Wang <wvw@google.com> wrote:
> > >
> > > Make cooling device registration behavior consistent with
> >
> > Consistent how? Please add details.
> >
> Consistent with
> https://lore.kernel.org/linux-pm/1478581767-7009-2-git-send-email-edubezval@gmail.com/
>
> will include aboce in next version.

Thanks.

>
> > > thermal zone. This patch also cleans up a unnecessary
> > > nullptr check.
> > >
> > > Signed-off-by: Wei Wang <wvw@google.com>
> > > ---
> > >  drivers/thermal/thermal_core.c | 16 ++++++++++++----
> > >  1 file changed, 12 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > index d4481cc8958f..64fbb59c2f44 100644
> > > --- a/drivers/thermal/thermal_core.c
> > > +++ b/drivers/thermal/thermal_core.c
> > > @@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct device_node *np,
> > >         struct thermal_zone_device *pos = NULL;
> > >         int result;
> > >
> > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > -               return ERR_PTR(-EINVAL);
> > > +       if (!type || !type[0]) {
> > > +           pr_err("Error: No cooling device type defined\n");
> > > +           return ERR_PTR(-EINVAL);
> > > +       }
> > > +
> > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > > +           pr_err("Error: Cooling device name (%s) too long, "
> > > +                  "should be under %d chars\n", type, THERMAL_NAME_LENGTH);
> >
> > Consider fitting into a single greppable string as "Error: Cooling
> > device name over %d chars: %s\n"
> >
> Was intentionally keep it the same as this
> https://lore.kernel.org/linux-pm/31a29628894a14e716fff113fd9ce945fe649c05.1562876950.git.amit.kucheria@linaro.org/
> Will make it shorter in both places next verion

Yes please, make it a separate patch. We didn't catch it during review.

>
> > > +           return ERR_PTR(-EINVAL);
> > > +       }
> > >
> > >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > >             !ops->set_cur_state)
> > > @@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > >         }
> > >
> > >         cdev->id = result;
> > > -       strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
> > > +       strlcpy(cdev->type, type, sizeof(cdev->type));
> > >         mutex_init(&cdev->lock);
> > >         INIT_LIST_HEAD(&cdev->thermal_instances);
> > >         cdev->np = np;
> > > @@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> > >                 return ERR_PTR(-EINVAL);
> > >         }
> > >
> > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
> > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > >                 pr_err("Error: Thermal zone name (%s) too long, should be under %d chars\n",
> > >                        type, THERMAL_NAME_LENGTH);
> > >                 return ERR_PTR(-EINVAL);
> > > --
> > > 2.24.0.393.g34dc348eaf-goog
> > >

Re: [PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Amit Kucheria]

On Thu, Dec 5, 2019 at 11:56 AM Amit Kucheria
<amit.kucheria@verdurent.com> wrote:
>
> On Thu, Dec 5, 2019 at 11:44 AM Wei Wang <wvw@google.com> wrote:
> >
> > On Wed, Dec 4, 2019 at 8:13 PM Amit Kucheria
> > <amit.kucheria@verdurent.com> wrote:
> > >
> > > Hi Wei,
> > >
> > > On Thu, Dec 5, 2019 at 3:26 AM Wei Wang <wvw@google.com> wrote:
> > > >
> > > > Make cooling device registration behavior consistent with
> > >
> > > Consistent how? Please add details.
> > >
> > Consistent with
> > https://lore.kernel.org/linux-pm/1478581767-7009-2-git-send-email-edubezval@gmail.com/

Studying this a bit more, git blame pointed to this SHA[1] that fixed
it so that NULL value for 'type' is allowed, we just check for it.
However, none of the users of thermal_cooling_device_register() seem
to pass NULL.

Rui, any insight into the history of why we would NOT want to create a
sysfs attribute by passing NULL? Do we still need to allow for NULL
values or should we cleanup the API to prevent NULL values?

[1] 204dd1d39c32f39a95


> >
> > will include aboce in next version.
>
> Thanks.
>
> >
> > > > thermal zone. This patch also cleans up a unnecessary
> > > > nullptr check.
> > > >
> > > > Signed-off-by: Wei Wang <wvw@google.com>
> > > > ---
> > > >  drivers/thermal/thermal_core.c | 16 ++++++++++++----
> > > >  1 file changed, 12 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > > > index d4481cc8958f..64fbb59c2f44 100644
> > > > --- a/drivers/thermal/thermal_core.c
> > > > +++ b/drivers/thermal/thermal_core.c
> > > > @@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct device_node *np,
> > > >         struct thermal_zone_device *pos = NULL;
> > > >         int result;
> > > >
> > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > > -               return ERR_PTR(-EINVAL);
> > > > +       if (!type || !type[0]) {
> > > > +           pr_err("Error: No cooling device type defined\n");
> > > > +           return ERR_PTR(-EINVAL);
> > > > +       }
> > > > +
> > > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > > > +           pr_err("Error: Cooling device name (%s) too long, "
> > > > +                  "should be under %d chars\n", type, THERMAL_NAME_LENGTH);
> > >
> > > Consider fitting into a single greppable string as "Error: Cooling
> > > device name over %d chars: %s\n"
> > >
> > Was intentionally keep it the same as this
> > https://lore.kernel.org/linux-pm/31a29628894a14e716fff113fd9ce945fe649c05.1562876950.git.amit.kucheria@linaro.org/
> > Will make it shorter in both places next verion
>
> Yes please, make it a separate patch. We didn't catch it during review.
>
> >
> > > > +           return ERR_PTR(-EINVAL);
> > > > +       }
> > > >
> > > >         if (!ops || !ops->get_max_state || !ops->get_cur_state ||
> > > >             !ops->set_cur_state)
> > > > @@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct device_node *np,
> > > >         }
> > > >
> > > >         cdev->id = result;
> > > > -       strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
> > > > +       strlcpy(cdev->type, type, sizeof(cdev->type));
> > > >         mutex_init(&cdev->lock);
> > > >         INIT_LIST_HEAD(&cdev->thermal_instances);
> > > >         cdev->np = np;
> > > > @@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char *type, int trips, int mask,
> > > >                 return ERR_PTR(-EINVAL);
> > > >         }
> > > >
> > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
> > > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > > >                 pr_err("Error: Thermal zone name (%s) too long, should be under %d chars\n",
> > > >                        type, THERMAL_NAME_LENGTH);
> > > >                 return ERR_PTR(-EINVAL);
> > > > --
> > > > 2.24.0.393.g34dc348eaf-goog
> > > >

Re: [PATCH v2 1/2] thermal: fix and clean up tz and cdev registration

[Zhang Rui]

On Thu, 2019-12-05 at 12:36 +0530, Amit Kucheria wrote:
> On Thu, Dec 5, 2019 at 11:56 AM Amit Kucheria
> <amit.kucheria@verdurent.com> wrote:
> > 
> > On Thu, Dec 5, 2019 at 11:44 AM Wei Wang <wvw@google.com> wrote:
> > > 
> > > On Wed, Dec 4, 2019 at 8:13 PM Amit Kucheria
> > > <amit.kucheria@verdurent.com> wrote:
> > > > 
> > > > Hi Wei,
> > > > 
> > > > On Thu, Dec 5, 2019 at 3:26 AM Wei Wang <wvw@google.com> wrote:
> > > > > 
> > > > > Make cooling device registration behavior consistent with
> > > > 
> > > > Consistent how? Please add details.
> > > > 
> > > 
> > > Consistent with
> > > 
https://lore.kernel.org/linux-pm/1478581767-7009-2-git-send-email-edubezval@gmail.com/
> 
> Studying this a bit more, git blame pointed to this SHA[1] that fixed
> it so that NULL value for 'type' is allowed, we just check for it.
> However, none of the users of thermal_cooling_device_register() seem
> to pass NULL.
> 
> Rui, any insight into the history of why we would NOT want to create
> a
> sysfs attribute by passing NULL?

Actually, I don't recall there is any requirement that wants to
register a cooling_device without "type".

>  Do we still need to allow for NULL
> values or should we cleanup the API to prevent NULL values?
> 
well, my suggestion is to make this (do NULL check) a separate patch
and see if we have any complains, if yes, we can revert it easily.

thanks,
rui

> [1] 204dd1d39c32f39a95
> 
> 
> > > 
> > > will include aboce in next version.
> > 
> > Thanks.
> > 
> > > 
> > > > > thermal zone. This patch also cleans up a unnecessary
> > > > > nullptr check.
> > > > > 
> > > > > Signed-off-by: Wei Wang <wvw@google.com>
> > > > > ---
> > > > >  drivers/thermal/thermal_core.c | 16 ++++++++++++----
> > > > >  1 file changed, 12 insertions(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/thermal/thermal_core.c
> > > > > b/drivers/thermal/thermal_core.c
> > > > > index d4481cc8958f..64fbb59c2f44 100644
> > > > > --- a/drivers/thermal/thermal_core.c
> > > > > +++ b/drivers/thermal/thermal_core.c
> > > > > @@ -954,8 +954,16 @@ __thermal_cooling_device_register(struct
> > > > > device_node *np,
> > > > >         struct thermal_zone_device *pos = NULL;
> > > > >         int result;
> > > > > 
> > > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> > > > > -               return ERR_PTR(-EINVAL);
> > > > > +       if (!type || !type[0]) {
> > > > > +           pr_err("Error: No cooling device type
> > > > > defined\n");
> > > > > +           return ERR_PTR(-EINVAL);
> > > > > +       }
> > > > > +
> > > > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > > > > +           pr_err("Error: Cooling device name (%s) too long,
> > > > > "
> > > > > +                  "should be under %d chars\n", type,
> > > > > THERMAL_NAME_LENGTH);
> > > > 
> > > > Consider fitting into a single greppable string as "Error:
> > > > Cooling
> > > > device name over %d chars: %s\n"
> > > > 
> > > 
> > > Was intentionally keep it the same as this
> > > 
https://lore.kernel.org/linux-pm/31a29628894a14e716fff113fd9ce945fe649c05.1562876950.git.amit.kucheria@linaro.org/
> > > Will make it shorter in both places next verion
> > 
> > Yes please, make it a separate patch. We didn't catch it during
> > review.
> > 
> > > 
> > > > > +           return ERR_PTR(-EINVAL);
> > > > > +       }
> > > > > 
> > > > >         if (!ops || !ops->get_max_state || !ops-
> > > > > >get_cur_state ||
> > > > >             !ops->set_cur_state)
> > > > > @@ -972,7 +980,7 @@ __thermal_cooling_device_register(struct
> > > > > device_node *np,
> > > > >         }
> > > > > 
> > > > >         cdev->id = result;
> > > > > -       strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
> > > > > +       strlcpy(cdev->type, type, sizeof(cdev->type));
> > > > >         mutex_init(&cdev->lock);
> > > > >         INIT_LIST_HEAD(&cdev->thermal_instances);
> > > > >         cdev->np = np;
> > > > > @@ -1250,7 +1258,7 @@ thermal_zone_device_register(const char
> > > > > *type, int trips, int mask,
> > > > >                 return ERR_PTR(-EINVAL);
> > > > >         }
> > > > > 
> > > > > -       if (type && strlen(type) >= THERMAL_NAME_LENGTH) {
> > > > > +       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> > > > >                 pr_err("Error: Thermal zone name (%s) too
> > > > > long, should be under %d chars\n",
> > > > >                        type, THERMAL_NAME_LENGTH);
> > > > >                 return ERR_PTR(-EINVAL);
> > > > > --
> > > > > 2.24.0.393.g34dc348eaf-goog
> > > > >