On Fri, Mar 12, 2021 at 02:04:08PM +0100, Daniel Lezcano wrote: > A SoC can be differently structured depending on the platform and the > kernel can not be aware of all the combinations, as well as the > specific tweaks for a particular board. > > The creation of the hierarchy must be delegated to userspace. > > These changes provide a registering mechanism where the different > subsystems will initialize their dtpm backends and register with a > name the dtpm node in a list. > > The next changes will provide an userspace interface to create > hierarchically the different nodes. Those will be created by name and > found via the list filled by the different subsystem. > > If a specified name is not found in the list, it is assumed to be a > virtual node which will have children and the default is to allocate > such node. > > When the node register in the list, the function will be dtpm_register > where the previous semantic was to create the node. Thus, the > functions are renamed to reflect their purpose. > > Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org> > Reviewed-by: Lukasz Luba <lukasz.l...@arm.com> > --- > > V4: > - Fixed typo in the commit log > > V2: > - Fixed error code path by dropping lock > --- > drivers/powercap/dtpm.c | 161 ++++++++++++++++++++++++++++++++++-- > drivers/powercap/dtpm_cpu.c | 4 +- > include/linux/dtpm.h | 12 ++- > 3 files changed, 164 insertions(+), 13 deletions(-) > > diff --git a/drivers/powercap/dtpm.c b/drivers/powercap/dtpm.c > index 58433b8ef9a1..d00f55f0ee30 100644 > --- a/drivers/powercap/dtpm.c > +++ b/drivers/powercap/dtpm.c > @@ -20,6 +20,7 @@ > #include <linux/dtpm.h> > #include <linux/init.h> > #include <linux/kernel.h> > +#include <linux/kref.h> > #include <linux/powercap.h> > #include <linux/slab.h> > #include <linux/mutex.h> > @@ -34,6 +35,14 @@ static DEFINE_MUTEX(dtpm_lock); > static struct powercap_control_type *pct; > static struct dtpm *root; > > +struct dtpm_node { > + const char *name; > + struct dtpm *dtpm; > + struct list_head node; > +}; > + > +static LIST_HEAD(dtpm_list); > + > static int get_time_window_us(struct powercap_zone *pcz, int cid, u64 > *window) > { > return -ENOSYS; > @@ -152,6 +161,138 @@ static int __dtpm_update_power(struct dtpm *dtpm) > return ret; > } > > +static struct dtpm *__dtpm_lookup(const char *name) > +{ > + struct dtpm_node *node; > + > + list_for_each_entry(node, &dtpm_list, node) { > + if (!strcmp(name, node->name)) > + return node->dtpm; > + } > + > + return NULL; > +} > + > +/** > + * dtpm_get - Get a reference to a dtpm structure > + * @name: the name of the dtpm device > + * > + * The function looks up in the list of the registered dtpm > + * devices. If the dtpm device is not found, a virtual one is > + * allocated. This function must be called to create a dtpm node in > + * the powercap hierarchy. > + * > + * Return: a pointer to a dtpm structure, NULL if there is not enough > + * memory > + */ > +struct dtpm *dtpm_get(const char *name) > +{ > + struct dtpm *dtpm; > + > + mutex_lock(&dtpm_lock); > + dtpm = __dtpm_lookup(name); > + if (!dtpm) > + dtpm = dtpm_alloc(NULL); > + else > + kref_get(&dtpm->kref); > + mutex_unlock(&dtpm_lock); > + > + return dtpm; > +} > + > +static void dtpm_release(struct kref *kref) > +{ > + struct dtpm *dtpm = container_of(kref, struct dtpm, kref); > + > + kfree(dtpm); > +} > + > +/** > + * dtpm_put - Release a reference on a dtpm device > + * @dtpm: a pointer to a dtpm structure > + * > + * Release the reference on the specified dtpm device. The last > + * reference leads to a memory release. > + */ > +void dtpm_put(struct dtpm *dtpm) > +{ > + kref_put(&dtpm->kref, dtpm_release);
You forgot to also grab the dtpm_lock before calling this, right? What is preventing a get and put from being called at the same time? You protect things at get time, but not put from what I can see :( > +} > + > +/** > + * dtpm_register - Register the dtpm in the dtpm list > + * @name: a name used as an identifier > + * @dtpm: the dtpm node to be registered > + * > + * Stores the dtpm device in a list. > + * > + * Return: 0 on success, -EEXIST if the device name is already present > + * in the list, -ENOMEM in case of memory allocation failure. > + */ > +int dtpm_register(const char *name, struct dtpm *dtpm) > +{ > + struct dtpm_node *node; > + int ret; > + > + mutex_lock(&dtpm_lock); > + > + ret = -EEXIST; > + if (__dtpm_lookup(name)) > + goto out_unlock; > + > + ret = -ENOMEM; > + node = kzalloc(sizeof(*node), GFP_KERNEL); > + if (!node) > + goto out_unlock; > + > + node->name = kstrdup(name, GFP_KERNEL); > + if (!node->name) { > + kfree(node); > + goto out_unlock; > + } > + > + node->dtpm = dtpm; > + > + list_add(&node->node, &dtpm_list); > + > + pr_info("Registered %s\n", name); When kernel code works properly, it is quiet. This is debugging code a the most, never something that everyone should be seeing all the time, please remove. > + > + ret = 0; > +out_unlock: > + mutex_unlock(&dtpm_lock); > + > + return ret; > +} > + > +/** > + * dtpm_unregister - Remove the dtpm device from the list > + * @name: the dtpm device name to be removed > + * > + * Remove the dtpm device from the list of the registered devices. > + */ > +void dtpm_unregister(const char *name) > +{ > + struct dtpm_node *node; > + > + mutex_lock(&dtpm_lock); > + > + list_for_each_entry(node, &dtpm_list, node) { > + > + if (strcmp(name, node->name)) > + continue; > + > + list_del(&node->node); > + kfree(node->name); > + kfree(node); > + > + pr_info("Unregistered %s\n", name); Again, debugging code should be removed. > + > + break; > + } > + > + mutex_unlock(&dtpm_lock); > +} > + > /** > * dtpm_update_power - Update the power on the dtpm > * @dtpm: a pointer to a dtpm structure to update > @@ -208,7 +349,7 @@ int dtpm_release_zone(struct powercap_zone *pcz) > if (root == dtpm) > root = NULL; > > - kfree(dtpm); > + dtpm_put(dtpm); > > return 0; > } > @@ -370,6 +511,7 @@ struct dtpm *dtpm_alloc(struct dtpm_ops *ops) > if (dtpm) { > INIT_LIST_HEAD(&dtpm->children); > INIT_LIST_HEAD(&dtpm->sibling); > + kref_init(&dtpm->kref); > dtpm->weight = 1024; > dtpm->ops = ops; > } > @@ -378,28 +520,29 @@ struct dtpm *dtpm_alloc(struct dtpm_ops *ops) > } > > /** > - * dtpm_unregister - Unregister a dtpm node from the hierarchy tree > - * @dtpm: a pointer to a dtpm structure corresponding to the node to be > removed > + * dtpm_destroy - Destroy a dtpm node from the hierarchy tree > + * @dtpm: a pointer to a dtpm structure corresponding to the node to be > + * removed and destroyed > * > * Call the underlying powercap unregister function. That will call > * the release callback of the powercap zone. > */ > -void dtpm_unregister(struct dtpm *dtpm) > +void dtpm_destroy(struct dtpm *dtpm) > { > powercap_unregister_zone(pct, &dtpm->zone); > > - pr_info("Unregistered dtpm node '%s'\n", dtpm->zone.name); > + pr_info("Destroyed dtpm node '%s'\n", dtpm->zone.name); Again, please make pr_dbg(). And any reason why you are not using "real" struct devices in this subsystem? You seem to be rolling your own infrastructure for no good reason. I imagine you want sysfs support next, right? thanks, greg k-h