On Wed, Oct 16, 2019 at 10:16 AM Amit Kucheria <amit.kuche...@verdurent.com> wrote: > > On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria > <amit.kuche...@verdurent.com> wrote: > > > > On Tue, Oct 15, 2019 at 11:43 AM Wei Wang <w...@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 <w...@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 > > >