Commit 56c807ba authored by Tejun Heo's avatar Tejun Heo

cgroup: add cgroup_subsys->css_e_css_changed()

Add a new cgroup_subsys operatoin ->css_e_css_changed().  This is
invoked if any of the effective csses seen from the css's cgroup may
have changed.  This will be used to implement cgroup writeback
support.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent 7d172cc8
......@@ -615,6 +615,7 @@ struct cgroup_subsys {
void (*css_released)(struct cgroup_subsys_state *css);
void (*css_free)(struct cgroup_subsys_state *css);
void (*css_reset)(struct cgroup_subsys_state *css);
void (*css_e_css_changed)(struct cgroup_subsys_state *css);
int (*can_attach)(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset);
......
......@@ -2836,6 +2836,24 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
}
}
/*
* 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:
......
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