if (!(cgrp->root->subsys_mask & (1 << ss->id)))
return NULL;
+ /*
+ * This function is used while updating css associations and thus
+ * can't test the csses directly. Use ->child_subsys_mask.
+ */
while (cgroup_parent(cgrp) &&
!(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id)))
cgrp = cgroup_parent(cgrp);
return cgroup_css(cgrp, ss);
}
+/**
+ * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get the effective css of @cgrp for @ss. The effective css is
+ * defined as the matching css of the nearest ancestor including self which
+ * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
+ * the root css is returned, so this function always returns a valid css.
+ * The returned css must be put using css_put().
+ */
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup_subsys_state *css;
+
+ rcu_read_lock();
+
+ do {
+ css = cgroup_css(cgrp, ss);
+
+ if (css && css_tryget_online(css))
+ goto out_unlock;
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+
+ css = init_css_set.subsys[ss->id];
+ css_get(css);
+out_unlock:
+ rcu_read_unlock();
+ return css;
+}
+
/* convenient tests for these bits */
static inline bool cgroup_is_dead(const struct cgroup *cgrp)
{
}
/**
- * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * cgroup_calc_child_subsys_mask - calculate child_subsys_mask
* @cgrp: the target cgroup
+ * @subtree_control: the new subtree_control mask to consider
*
* On the default hierarchy, a subsystem may request other subsystems to be
* enabled together through its ->depends_on mask. In such cases, more
* subsystems than specified in "cgroup.subtree_control" may be enabled.
*
- * This function determines which subsystems need to be enabled given the
- * current @cgrp->subtree_control and records it in
- * @cgrp->child_subsys_mask. The resulting mask is always a superset of
- * @cgrp->subtree_control and follows the usual hierarchy rules.
+ * This function calculates which subsystems need to be enabled if
+ * @subtree_control is to be applied to @cgrp. The returned mask is always
+ * a superset of @subtree_control and follows the usual hierarchy rules.
*/
-static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+static unsigned int cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
+ unsigned int subtree_control)
{
struct cgroup *parent = cgroup_parent(cgrp);
- unsigned int cur_ss_mask = cgrp->subtree_control;
+ unsigned int cur_ss_mask = subtree_control;
struct cgroup_subsys *ss;
int ssid;
lockdep_assert_held(&cgroup_mutex);
- if (!cgroup_on_dfl(cgrp)) {
- cgrp->child_subsys_mask = cur_ss_mask;
- return;
- }
+ if (!cgroup_on_dfl(cgrp))
+ return cur_ss_mask;
while (true) {
unsigned int new_ss_mask = cur_ss_mask;
cur_ss_mask = new_ss_mask;
}
- cgrp->child_subsys_mask = cur_ss_mask;
+ return cur_ss_mask;
+}
+
+/**
+ * cgroup_refresh_child_subsys_mask - update child_subsys_mask
+ * @cgrp: the target cgroup
+ *
+ * Update @cgrp->child_subsys_mask according to the current
+ * @cgrp->subtree_control using cgroup_calc_child_subsys_mask().
+ */
+static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp)
+{
+ cgrp->child_subsys_mask =
+ cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control);
}
/**
loff_t off)
{
unsigned int enable = 0, disable = 0;
- unsigned int css_enable, css_disable, old_ctrl, new_ctrl;
+ unsigned int css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
struct cgroup *cgrp, *child;
struct cgroup_subsys *ss;
char *tok;
ret = -ENOENT;
goto out_unlock;
}
-
- /*
- * @ss is already enabled through dependency and
- * we'll just make it visible. Skip draining.
- */
- if (cgrp->child_subsys_mask & (1 << ssid))
- continue;
-
- /*
- * Because css offlining is asynchronous, userland
- * might try to re-enable the same controller while
- * the previous instance is still around. In such
- * cases, wait till it's gone using offline_waitq.
- */
- cgroup_for_each_live_child(child, cgrp) {
- DEFINE_WAIT(wait);
-
- if (!cgroup_css(child, ss))
- continue;
-
- cgroup_get(child);
- prepare_to_wait(&child->offline_waitq, &wait,
- TASK_UNINTERRUPTIBLE);
- cgroup_kn_unlock(of->kn);
- schedule();
- finish_wait(&child->offline_waitq, &wait);
- cgroup_put(child);
-
- return restart_syscall();
- }
} else if (disable & (1 << ssid)) {
if (!(cgrp->subtree_control & (1 << ssid))) {
disable &= ~(1 << ssid);
* subsystems than specified may need to be enabled or disabled
* depending on subsystem dependencies.
*/
- cgrp->subtree_control |= enable;
- cgrp->subtree_control &= ~disable;
+ old_sc = cgrp->subtree_control;
+ old_ss = cgrp->child_subsys_mask;
+ new_sc = (old_sc | enable) & ~disable;
+ new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc);
- old_ctrl = cgrp->child_subsys_mask;
- cgroup_refresh_child_subsys_mask(cgrp);
- new_ctrl = cgrp->child_subsys_mask;
-
- css_enable = ~old_ctrl & new_ctrl;
- css_disable = old_ctrl & ~new_ctrl;
+ css_enable = ~old_ss & new_ss;
+ css_disable = old_ss & ~new_ss;
enable |= css_enable;
disable |= css_disable;
+ /*
+ * Because css offlining is asynchronous, userland might try to
+ * re-enable the same controller while the previous instance is
+ * still around. In such cases, wait till it's gone using
+ * offline_waitq.
+ */
+ for_each_subsys(ss, ssid) {
+ if (!(css_enable & (1 << ssid)))
+ continue;
+
+ cgroup_for_each_live_child(child, cgrp) {
+ DEFINE_WAIT(wait);
+
+ if (!cgroup_css(child, ss))
+ continue;
+
+ cgroup_get(child);
+ prepare_to_wait(&child->offline_waitq, &wait,
+ TASK_UNINTERRUPTIBLE);
+ cgroup_kn_unlock(of->kn);
+ schedule();
+ finish_wait(&child->offline_waitq, &wait);
+ cgroup_put(child);
+
+ return restart_syscall();
+ }
+ }
+
+ cgrp->subtree_control = new_sc;
+ cgrp->child_subsys_mask = new_ss;
+
/*
* Create new csses or make the existing ones visible. A css is
* created invisible if it's being implicitly enabled through
}
}
+ /*
+ * The effective csses of all the descendants (excluding @cgrp) may
+ * have changed. Subsystems can optionally subscribe to this event
+ * by implementing ->css_e_css_changed() which is invoked if any of
+ * the effective csses seen from the css's cgroup may have changed.
+ */
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss);
+ struct cgroup_subsys_state *css;
+
+ if (!ss->css_e_css_changed || !this_css)
+ continue;
+
+ css_for_each_descendant_pre(css, this_css)
+ if (css != this_css)
+ ss->css_e_css_changed(css);
+ }
+
kernfs_activate(cgrp->kn);
ret = 0;
out_unlock:
return ret ?: nbytes;
err_undo_css:
- cgrp->subtree_control &= ~enable;
- cgrp->subtree_control |= disable;
- cgroup_refresh_child_subsys_mask(cgrp);
+ cgrp->subtree_control = old_sc;
+ cgrp->child_subsys_mask = old_ss;
for_each_subsys(ss, ssid) {
if (!(enable & (1 << ssid)))
if (ss) {
/* css release path */
cgroup_idr_remove(&ss->css_idr, css->id);
+ if (ss->css_released)
+ ss->css_released(css);
} else {
/* cgroup release path */
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
projects / cascardo / linux.git / blobdiff