[PATCH v2] genpd: Fix up terminology with parent/child

Kees Cook
2020-07-08T23:32:18Z

The genpd infrastructure uses the terms master/slave, but such uses have
no external exposures (not even in Documentation/driver-api/pm/*) and are
not mandated by nor associated with any external specifications. Change
the language used through-out to parent/child.

There was one possible exception in the debugfs node
"pm_genpd/pm_genpd_summary" but its path has no hits outside of the
kernel itself when performing a code search[1], and it seems even this
single usage has been non-functional since it was introduced due to a
typo in the Python ("apend" instead of correct "append"). Fix the typo
while we're at it.

[1] https://codesearch.debian.net/

Signed-off-by: Kees Cook <keescook@chromium.org>
---
v2: leader/follower -> parent/child (ulf, rafael)
v1: https://lore.kernel.org/lkml/202007080131.3E6D0858@keescook
This is motivated by the recent discussions over coding style:
https://lore.kernel.org/lkml/159419296487.2464622.863943877093636532.stgit@dwillia2-desk3.amr.corp.intel.com/
---
drivers/base/power/domain.c | 194 +++++++++++++--------------
drivers/base/power/domain_governor.c | 12 +-
include/linux/pm_domain.h | 12 +-
scripts/gdb/linux/genpd.py | 12 +-
4 files changed, 115 insertions(+), 115 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 0a01df608849..2cb5e04cf86c 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -263,18 +263,18 @@ static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
/*
* Traverse all sub-domains within the domain. This can be
* done without any additional locking as the link->performance_state
- * field is protected by the master genpd->lock, which is already taken.
+ * field is protected by the parent genpd->lock, which is already taken.
*
* Also note that link->performance_state (subdomain's performance state
- * requirement to master domain) is different from
- * link->slave->performance_state (current performance state requirement
+ * requirement to parent domain) is different from
+ * link->child->performance_state (current performance state requirement
* of the devices/sub-domains of the subdomain) and so can have a
* different value.
*
* Note that we also take vote from powered-off sub-domains into account
* as the same is done for devices right now.
*/
- list_for_each_entry(link, &genpd->master_links, master_node) {
+ list_for_each_entry(link, &genpd->parent_links, parent_node) {
if (link->performance_state > state)
state = link->performance_state;
}
@@ -285,40 +285,40 @@ static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
static int _genpd_set_performance_state(struct generic_pm_domain *genpd,
unsigned int state, int depth)
{
- struct generic_pm_domain *master;
+ struct generic_pm_domain *parent;
struct gpd_link *link;
- int master_state, ret;
+ int parent_state, ret;

if (state == genpd->performance_state)
return 0;

- /* Propagate to masters of genpd */
- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- master = link->master;
+ /* Propagate to parents of genpd */
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ parent = link->parent;

- if (!master->set_performance_state)
+ if (!parent->set_performance_state)
continue;

- /* Find master's performance state */
+ /* Find parent's performance state */
ret = dev_pm_opp_xlate_performance_state(genpd->opp_table,
- master->opp_table,
+ parent->opp_table,
state);
if (unlikely(ret < 0))
goto err;

- master_state = ret;
+ parent_state = ret;

- genpd_lock_nested(master, depth + 1);
+ genpd_lock_nested(parent, depth + 1);

link->prev_performance_state = link->performance_state;
- link->performance_state = master_state;
- master_state = _genpd_reeval_performance_state(master,
- master_state);
- ret = _genpd_set_performance_state(master, master_state, depth + 1);
+ link->performance_state = parent_state;
+ parent_state = _genpd_reeval_performance_state(parent,
+ parent_state);
+ ret = _genpd_set_performance_state(parent, parent_state, depth + 1);
if (ret)
link->performance_state = link->prev_performance_state;

- genpd_unlock(master);
+ genpd_unlock(parent);

if (ret)
goto err;
@@ -333,26 +333,26 @@ static int _genpd_set_performance_state(struct generic_pm_domain *genpd,

err:
/* Encountered an error, lets rollback */
- list_for_each_entry_continue_reverse(link, &genpd->slave_links,
- slave_node) {
- master = link->master;
+ list_for_each_entry_continue_reverse(link, &genpd->child_links,
+ child_node) {
+ parent = link->parent;

- if (!master->set_performance_state)
+ if (!parent->set_performance_state)
continue;

- genpd_lock_nested(master, depth + 1);
+ genpd_lock_nested(parent, depth + 1);

- master_state = link->prev_performance_state;
- link->performance_state = master_state;
+ parent_state = link->prev_performance_state;
+ link->performance_state = parent_state;

- master_state = _genpd_reeval_performance_state(master,
- master_state);
- if (_genpd_set_performance_state(master, master_state, depth + 1)) {
+ parent_state = _genpd_reeval_performance_state(parent,
+ parent_state);
+ if (_genpd_set_performance_state(parent, parent_state, depth + 1)) {
pr_err("%s: Failed to roll back to %d performance state\n",
- master->name, master_state);
+ parent->name, parent_state);
}

- genpd_unlock(master);
+ genpd_unlock(parent);
}

return ret;
@@ -552,7 +552,7 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,

/*
* If sd_count > 0 at this point, one of the subdomains hasn't
- * managed to call genpd_power_on() for the master yet after
+ * managed to call genpd_power_on() for the parent yet after
* incrementing it. In that case genpd_power_on() will wait
* for us to drop the lock, so we can call .power_off() and let
* the genpd_power_on() restore power for us (this shouldn't
@@ -566,22 +566,22 @@ static int genpd_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
genpd->status = GPD_STATE_POWER_OFF;
genpd_update_accounting(genpd);

- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- genpd_sd_counter_dec(link->master);
- genpd_lock_nested(link->master, depth + 1);
- genpd_power_off(link->master, false, depth + 1);
- genpd_unlock(link->master);
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ genpd_sd_counter_dec(link->parent);
+ genpd_lock_nested(link->parent, depth + 1);
+ genpd_power_off(link->parent, false, depth + 1);
+ genpd_unlock(link->parent);
}

return 0;
}

/**
- * genpd_power_on - Restore power to a given PM domain and its masters.
+ * genpd_power_on - Restore power to a given PM domain and its parents.
* @genpd: PM domain to power up.
* @depth: nesting count for lockdep.
*
- * Restore power to @genpd and all of its masters so that it is possible to
+ * Restore power to @genpd and all of its parents so that it is possible to
* resume a device belonging to it.
*/
static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
@@ -594,20 +594,20 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)

/*
* The list is guaranteed not to change while the loop below is being
- * executed, unless one of the masters' .power_on() callbacks fiddles
+ * executed, unless one of the parents' .power_on() callbacks fiddles
* with it.
*/
- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- struct generic_pm_domain *master = link->master;
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ struct generic_pm_domain *parent = link->parent;

- genpd_sd_counter_inc(master);
+ genpd_sd_counter_inc(parent);

- genpd_lock_nested(master, depth + 1);
- ret = genpd_power_on(master, depth + 1);
- genpd_unlock(master);
+ genpd_lock_nested(parent, depth + 1);
+ ret = genpd_power_on(parent, depth + 1);
+ genpd_unlock(parent);

if (ret) {
- genpd_sd_counter_dec(master);
+ genpd_sd_counter_dec(parent);
goto err;
}
}
@@ -623,12 +623,12 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)

err:
list_for_each_entry_continue_reverse(link,
- &genpd->slave_links,
- slave_node) {
- genpd_sd_counter_dec(link->master);
- genpd_lock_nested(link->master, depth + 1);
- genpd_power_off(link->master, false, depth + 1);
- genpd_unlock(link->master);
+ &genpd->child_links,
+ child_node) {
+ genpd_sd_counter_dec(link->parent);
+ genpd_lock_nested(link->parent, depth + 1);
+ genpd_power_off(link->parent, false, depth + 1);
+ genpd_unlock(link->parent);
}

return ret;
@@ -932,13 +932,13 @@ late_initcall(genpd_power_off_unused);
#ifdef CONFIG_PM_SLEEP

/**
- * genpd_sync_power_off - Synchronously power off a PM domain and its masters.
+ * genpd_sync_power_off - Synchronously power off a PM domain and its parents.
* @genpd: PM domain to power off, if possible.
* @use_lock: use the lock.
* @depth: nesting count for lockdep.
*
* Check if the given PM domain can be powered off (during system suspend or
- * hibernation) and do that if so. Also, in that case propagate to its masters.
+ * hibernation) and do that if so. Also, in that case propagate to its parents.
*
* This function is only called in "noirq" and "syscore" stages of system power
* transitions. The "noirq" callbacks may be executed asynchronously, thus in
@@ -963,21 +963,21 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,

genpd->status = GPD_STATE_POWER_OFF;

- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- genpd_sd_counter_dec(link->master);
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ genpd_sd_counter_dec(link->parent);

if (use_lock)
- genpd_lock_nested(link->master, depth + 1);
+ genpd_lock_nested(link->parent, depth + 1);

- genpd_sync_power_off(link->master, use_lock, depth + 1);
+ genpd_sync_power_off(link->parent, use_lock, depth + 1);

if (use_lock)
- genpd_unlock(link->master);
+ genpd_unlock(link->parent);
}
}

/**
- * genpd_sync_power_on - Synchronously power on a PM domain and its masters.
+ * genpd_sync_power_on - Synchronously power on a PM domain and its parents.
* @genpd: PM domain to power on.
* @use_lock: use the lock.
* @depth: nesting count for lockdep.
@@ -994,16 +994,16 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
if (genpd_status_on(genpd))
return;

- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- genpd_sd_counter_inc(link->master);
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ genpd_sd_counter_inc(link->parent);

if (use_lock)
- genpd_lock_nested(link->master, depth + 1);
+ genpd_lock_nested(link->parent, depth + 1);

- genpd_sync_power_on(link->master, use_lock, depth + 1);
+ genpd_sync_power_on(link->parent, use_lock, depth + 1);

if (use_lock)
- genpd_unlock(link->master);
+ genpd_unlock(link->parent);
}

_genpd_power_on(genpd, false);
@@ -1443,12 +1443,12 @@ static void genpd_update_cpumask(struct generic_pm_domain *genpd,
if (!genpd_is_cpu_domain(genpd))
return;

- list_for_each_entry(link, &genpd->slave_links, slave_node) {
- struct generic_pm_domain *master = link->master;
+ list_for_each_entry(link, &genpd->child_links, child_node) {
+ struct generic_pm_domain *parent = link->parent;

- genpd_lock_nested(master, depth + 1);
- genpd_update_cpumask(master, cpu, set, depth + 1);
- genpd_unlock(master);
+ genpd_lock_nested(parent, depth + 1);
+ genpd_update_cpumask(parent, cpu, set, depth + 1);
+ genpd_unlock(parent);
}

if (set)
@@ -1636,17 +1636,17 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,
goto out;
}

- list_for_each_entry(itr, &genpd->master_links, master_node) {
- if (itr->slave == subdomain && itr->master == genpd) {
+ list_for_each_entry(itr, &genpd->parent_links, parent_node) {
+ if (itr->child == subdomain && itr->parent == genpd) {
ret = -EINVAL;
goto out;
}
}

- link->master = genpd;
- list_add_tail(&link->master_node, &genpd->master_links);
- link->slave = subdomain;
- list_add_tail(&link->slave_node, &subdomain->slave_links);
+ link->parent = genpd;
+ list_add_tail(&link->parent_node, &genpd->parent_links);
+ link->child = subdomain;
+ list_add_tail(&link->child_node, &subdomain->child_links);
if (genpd_status_on(subdomain))
genpd_sd_counter_inc(genpd);

@@ -1660,7 +1660,7 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,

/**
* pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
- * @genpd: Master PM domain to add the subdomain to.
+ * @genpd: Leader PM domain to add the subdomain to.
* @subdomain: Subdomain to be added.
*/
int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
@@ -1678,7 +1678,7 @@ EXPORT_SYMBOL_GPL(pm_genpd_add_subdomain);

/**
* pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
- * @genpd: Master PM domain to remove the subdomain from.
+ * @genpd: Leader PM domain to remove the subdomain from.
* @subdomain: Subdomain to be removed.
*/
int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
@@ -1693,19 +1693,19 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
genpd_lock(subdomain);
genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);

- if (!list_empty(&subdomain->master_links) || subdomain->device_count) {
+ if (!list_empty(&subdomain->parent_links) || subdomain->device_count) {
pr_warn("%s: unable to remove subdomain %s\n",
genpd->name, subdomain->name);
ret = -EBUSY;
goto out;
}

- list_for_each_entry_safe(link, l, &genpd->master_links, master_node) {
- if (link->slave != subdomain)
+ list_for_each_entry_safe(link, l, &genpd->parent_links, parent_node) {
+ if (link->child != subdomain)
continue;

- list_del(&link->master_node);
- list_del(&link->slave_node);
+ list_del(&link->parent_node);
+ list_del(&link->child_node);
kfree(link);
if (genpd_status_on(subdomain))
genpd_sd_counter_dec(genpd);
@@ -1770,8 +1770,8 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
if (IS_ERR_OR_NULL(genpd))
return -EINVAL;

- INIT_LIST_HEAD(&genpd->master_links);
- INIT_LIST_HEAD(&genpd->slave_links);
+ INIT_LIST_HEAD(&genpd->parent_links);
+ INIT_LIST_HEAD(&genpd->child_links);
INIT_LIST_HEAD(&genpd->dev_list);
genpd_lock_init(genpd);
genpd->gov = gov;
@@ -1848,15 +1848,15 @@ static int genpd_remove(struct generic_pm_domain *genpd)
return -EBUSY;
}

- if (!list_empty(&genpd->master_links) || genpd->device_count) {
+ if (!list_empty(&genpd->parent_links) || genpd->device_count) {
genpd_unlock(genpd);
pr_err("%s: unable to remove %s\n", __func__, genpd->name);
return -EBUSY;
}

- list_for_each_entry_safe(link, l, &genpd->slave_links, slave_node) {
- list_del(&link->master_node);
- list_del(&link->slave_node);
+ list_for_each_entry_safe(link, l, &genpd->child_links, child_node) {
+ list_del(&link->parent_node);
+ list_del(&link->child_node);
kfree(link);
}

@@ -2827,12 +2827,12 @@ static int genpd_summary_one(struct seq_file *s,

/*
* Modifications on the list require holding locks on both
- * master and slave, so we are safe.
+ * parent and child, so we are safe.
* Also genpd->name is immutable.
*/
- list_for_each_entry(link, &genpd->master_links, master_node) {
- seq_printf(s, "%s", link->slave->name);
- if (!list_is_last(&link->master_node, &genpd->master_links))
+ list_for_each_entry(link, &genpd->parent_links, parent_node) {
+ seq_printf(s, "%s", link->child->name);
+ if (!list_is_last(&link->parent_node, &genpd->parent_links))
seq_puts(s, ", ");
}

@@ -2860,7 +2860,7 @@ static int summary_show(struct seq_file *s, void *data)
struct generic_pm_domain *genpd;
int ret = 0;

- seq_puts(s, "domain status slaves\n");
+ seq_puts(s, "domain status children\n");
seq_puts(s, " /device runtime status\n");
seq_puts(s, "----------------------------------------------------------------------\n");

@@ -2915,8 +2915,8 @@ static int sub_domains_show(struct seq_file *s, void *data)
if (ret)
return -ERESTARTSYS;

- list_for_each_entry(link, &genpd->master_links, master_node)
- seq_printf(s, "%s\n", link->slave->name);
+ list_for_each_entry(link, &genpd->parent_links, parent_node)
+ seq_printf(s, "%s\n", link->child->name);

genpd_unlock(genpd);
return ret;
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
index daa8c7689f7e..490ed7deb99a 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -135,8 +135,8 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
*
* All subdomains have been powered off already at this point.
*/
- list_for_each_entry(link, &genpd->master_links, master_node) {
- struct generic_pm_domain *sd = link->slave;
+ list_for_each_entry(link, &genpd->parent_links, parent_node) {
+ struct generic_pm_domain *sd = link->child;
s64 sd_max_off_ns = sd->max_off_time_ns;

if (sd_max_off_ns < 0)
@@ -217,13 +217,13 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
}

/*
- * We have to invalidate the cached results for the masters, so
+ * We have to invalidate the cached results for the parents, so
* use the observation that default_power_down_ok() is not
- * going to be called for any master until this instance
+ * going to be called for any parent until this instance
* returns.
*/
- list_for_each_entry(link, &genpd->slave_links, slave_node)
- link->master->max_off_time_changed = true;
+ list_for_each_entry(link, &genpd->child_links, child_node)
+ link->parent->max_off_time_changed = true;

genpd->max_off_time_ns = -1;
genpd->max_off_time_changed = false;
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 9ec78ee53652..574a1fadb1e5 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -95,8 +95,8 @@ struct generic_pm_domain {
struct device dev;
struct dev_pm_domain domain; /* PM domain operations */
struct list_head gpd_list_node; /* Node in the global PM domains list */
- struct list_head master_links; /* Links with PM domain as a master */
- struct list_head slave_links; /* Links with PM domain as a slave */
+ struct list_head parent_links; /* Links with PM domain as a parent */
+ struct list_head child_links;/* Links with PM domain as a child */
struct list_head dev_list; /* List of devices */
struct dev_power_governor *gov;
struct work_struct power_off_work;
@@ -151,10 +151,10 @@ static inline struct generic_pm_domain *pd_to_genpd(struct dev_pm_domain *pd)
}

struct gpd_link {
- struct generic_pm_domain *master;
- struct list_head master_node;
- struct generic_pm_domain *slave;
- struct list_head slave_node;
+ struct generic_pm_domain *parent;
+ struct list_head parent_node;
+ struct generic_pm_domain *child;
+ struct list_head child_node;

/* Sub-domain's per-master domain performance state */
unsigned int performance_state;
diff --git a/scripts/gdb/linux/genpd.py b/scripts/gdb/linux/genpd.py
index 6ca93bd2949e..39cd1abd8559 100644
--- a/scripts/gdb/linux/genpd.py
+++ b/scripts/gdb/linux/genpd.py
@@ -49,17 +49,17 @@ Output is similar to /sys/kernel/debug/pm_genpd/pm_genpd_summary'''
else:
status_string = 'off-{}'.format(genpd['state_idx'])

- slave_names = []
+ child_names = []
for link in list_for_each_entry(
- genpd['master_links'],
+ genpd['parent_links'],
device_link_type.get_type().pointer(),
- 'master_node'):
- slave_names.apend(link['slave']['name'])
+ 'parent_node'):
+ child_names.append(link['child']['name'])

gdb.write('%-30s %-15s %s\n' % (
genpd['name'].string(),
status_string,
- ', '.join(slave_names)))
+ ', '.join(child_names)))

# Print devices in domain
for pm_data in list_for_each_entry(genpd['dev_list'],
@@ -70,7 +70,7 @@ Output is similar to /sys/kernel/debug/pm_genpd/pm_genpd_summary'''
gdb.write(' %-50s %s\n' % (kobj_path, rtpm_status_str(dev)))

def invoke(self, arg, from_tty):
- gdb.write('domain status slaves\n');
+ gdb.write('domain status children\n');
gdb.write(' /device runtime status\n');
gdb.write('----------------------------------------------------------------------\n');
for genpd in list_for_each_entry(
--
2.25.1

--
Kees Cook