cgroup: make cgroup_event hold onto cgroup_subsys_state instead of cgroup
Currently, each registered cgroup_event holds an extra reference to the cgroup. This is a bit weird as events are subsystem specific and will also be incorrect in the planned unified hierarchy as css (cgroup_subsys_state) may come and go dynamically across the lifetime of a cgroup. Holding onto cgroup won't prevent the target css from going away. Update cgroup_event to hold onto the css the traget file belongs to instead of cgroup. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
This commit is contained in:
parent
9fa4db334c
commit
7941cb027d
|
@ -3969,7 +3969,6 @@ static void cgroup_event_remove(struct work_struct *work)
|
||||||
struct cgroup_event *event = container_of(work, struct cgroup_event,
|
struct cgroup_event *event = container_of(work, struct cgroup_event,
|
||||||
remove);
|
remove);
|
||||||
struct cgroup_subsys_state *css = event->css;
|
struct cgroup_subsys_state *css = event->css;
|
||||||
struct cgroup *cgrp = css->cgroup;
|
|
||||||
|
|
||||||
remove_wait_queue(event->wqh, &event->wait);
|
remove_wait_queue(event->wqh, &event->wait);
|
||||||
|
|
||||||
|
@ -3980,7 +3979,7 @@ static void cgroup_event_remove(struct work_struct *work)
|
||||||
|
|
||||||
eventfd_ctx_put(event->eventfd);
|
eventfd_ctx_put(event->eventfd);
|
||||||
kfree(event);
|
kfree(event);
|
||||||
cgroup_dput(cgrp);
|
css_put(css);
|
||||||
}
|
}
|
||||||
|
|
||||||
/*
|
/*
|
||||||
|
@ -4103,12 +4102,16 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
|
||||||
goto out_put_cfile;
|
goto out_put_cfile;
|
||||||
}
|
}
|
||||||
|
|
||||||
/* determine the css of @cfile and associate @event with it */
|
/*
|
||||||
|
* Determine the css of @cfile and associate @event with it.
|
||||||
|
* Remaining events are automatically removed on cgroup destruction
|
||||||
|
* but the removal is asynchronous, so take an extra ref.
|
||||||
|
*/
|
||||||
rcu_read_lock();
|
rcu_read_lock();
|
||||||
|
|
||||||
ret = -EINVAL;
|
ret = -EINVAL;
|
||||||
event->css = cgroup_css(cgrp, event->cft->ss);
|
event->css = cgroup_css(cgrp, event->cft->ss);
|
||||||
if (event->css)
|
if (event->css && css_tryget(event->css))
|
||||||
ret = 0;
|
ret = 0;
|
||||||
|
|
||||||
rcu_read_unlock();
|
rcu_read_unlock();
|
||||||
|
@ -4122,28 +4125,21 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
|
||||||
cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
|
cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent);
|
||||||
if (cgrp_cfile != cgrp) {
|
if (cgrp_cfile != cgrp) {
|
||||||
ret = -EINVAL;
|
ret = -EINVAL;
|
||||||
goto out_put_cfile;
|
goto out_put_css;
|
||||||
}
|
}
|
||||||
|
|
||||||
if (!event->cft->register_event || !event->cft->unregister_event) {
|
if (!event->cft->register_event || !event->cft->unregister_event) {
|
||||||
ret = -EINVAL;
|
ret = -EINVAL;
|
||||||
goto out_put_cfile;
|
goto out_put_css;
|
||||||
}
|
}
|
||||||
|
|
||||||
ret = event->cft->register_event(event->css, event->cft,
|
ret = event->cft->register_event(event->css, event->cft,
|
||||||
event->eventfd, buffer);
|
event->eventfd, buffer);
|
||||||
if (ret)
|
if (ret)
|
||||||
goto out_put_cfile;
|
goto out_put_css;
|
||||||
|
|
||||||
efile->f_op->poll(efile, &event->pt);
|
efile->f_op->poll(efile, &event->pt);
|
||||||
|
|
||||||
/*
|
|
||||||
* Events should be removed after rmdir of cgroup directory, but before
|
|
||||||
* destroying subsystem state objects. Let's take reference to cgroup
|
|
||||||
* directory dentry to do that.
|
|
||||||
*/
|
|
||||||
dget(cgrp->dentry);
|
|
||||||
|
|
||||||
spin_lock(&cgrp->event_list_lock);
|
spin_lock(&cgrp->event_list_lock);
|
||||||
list_add(&event->list, &cgrp->event_list);
|
list_add(&event->list, &cgrp->event_list);
|
||||||
spin_unlock(&cgrp->event_list_lock);
|
spin_unlock(&cgrp->event_list_lock);
|
||||||
|
@ -4153,6 +4149,8 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *dummy_css,
|
||||||
|
|
||||||
return 0;
|
return 0;
|
||||||
|
|
||||||
|
out_put_css:
|
||||||
|
css_put(event->css);
|
||||||
out_put_cfile:
|
out_put_cfile:
|
||||||
fput(cfile);
|
fput(cfile);
|
||||||
out_put_eventfd:
|
out_put_eventfd:
|
||||||
|
|
Loading…
Reference in New Issue