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authorTejun Heo <tj@kernel.org>2015-09-18 17:54:23 -0400
committerTejun Heo <tj@kernel.org>2015-09-18 17:54:23 -0400
commit6f60eade2433cb3a38687d5f8a4f44b92c6c51bf (patch)
tree0c92e0b5bc6ae4c51c95a5917559e91992acb616 /kernel/cgroup.c
parent4df8dc903161c03cd9bff9077d8427fefe808e6d (diff)
downloadlwn-6f60eade2433cb3a38687d5f8a4f44b92c6c51bf.tar.gz
lwn-6f60eade2433cb3a38687d5f8a4f44b92c6c51bf.zip
cgroup: generalize obtaining the handles of and notifying cgroup files
cgroup core handles creations and removals of cgroup interface files as described by cftypes. There are cases where the handle for a given file instance is necessary, for example, to generate a file modified event. Currently, this is handled by explicitly matching the callback method pointer and storing the file handle manually in cgroup_add_file(). While this simple approach works for cgroup core files, it can't for controller interface files. This patch generalizes cgroup interface file handle handling. struct cgroup_file is defined and each cftype can optionally tell cgroup core to store the file handle by setting ->file_offset. A file handle remains accessible as long as the containing css is accessible. Both "cgroup.procs" and "cgroup.events" are converted to use the new generic mechanism instead of hooking directly into cgroup_add_file(). Also, cgroup_file_notify() which takes a struct cgroup_file and generates a file modified event on it is added and replaces explicit kernfs_notify() invocations. This generalizes cgroup file handle handling and allows controllers to generate file modified notifications. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c26
1 files changed, 19 insertions, 7 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 06c9d1aeea9d..0be276ffe08a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -612,8 +612,8 @@ static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
if (!trigger)
break;
- if (cgrp->events_kn)
- kernfs_notify(cgrp->events_kn);
+ cgroup_file_notify(&cgrp->events_file);
+
cgrp = cgroup_parent(cgrp);
} while (cgrp);
}
@@ -1771,6 +1771,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->self.sibling);
INIT_LIST_HEAD(&cgrp->self.children);
+ INIT_LIST_HEAD(&cgrp->self.files);
INIT_LIST_HEAD(&cgrp->cset_links);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
@@ -2562,7 +2563,7 @@ static int cgroup_procs_write_permission(struct task_struct *task,
cgrp = cgroup_parent(cgrp);
ret = -ENOMEM;
- inode = kernfs_get_inode(sb, cgrp->procs_kn);
+ inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
if (inode) {
ret = inode_permission(inode, MAY_WRITE);
iput(inode);
@@ -3253,10 +3254,14 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
return ret;
}
- if (cft->write == cgroup_procs_write)
- cgrp->procs_kn = kn;
- else if (cft->seq_show == cgroup_events_show)
- cgrp->events_kn = kn;
+ if (cft->file_offset) {
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ kernfs_get(kn);
+ cfile->kn = kn;
+ list_add(&cfile->node, &css->files);
+ }
+
return 0;
}
@@ -4408,6 +4413,7 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
static struct cftype cgroup_dfl_base_files[] = {
{
.name = "cgroup.procs",
+ .file_offset = offsetof(struct cgroup, procs_file),
.seq_start = cgroup_pidlist_start,
.seq_next = cgroup_pidlist_next,
.seq_stop = cgroup_pidlist_stop,
@@ -4433,6 +4439,7 @@ static struct cftype cgroup_dfl_base_files[] = {
{
.name = "cgroup.events",
.flags = CFTYPE_NOT_ON_ROOT,
+ .file_offset = offsetof(struct cgroup, events_file),
.seq_show = cgroup_events_show,
},
{ } /* terminate */
@@ -4511,9 +4518,13 @@ static void css_free_work_fn(struct work_struct *work)
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup_subsys *ss = css->ss;
struct cgroup *cgrp = css->cgroup;
+ struct cgroup_file *cfile;
percpu_ref_exit(&css->refcnt);
+ list_for_each_entry(cfile, &css->files, node)
+ kernfs_put(cfile->kn);
+
if (ss) {
/* css free path */
int id = css->id;
@@ -4618,6 +4629,7 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
css->ss = ss;
INIT_LIST_HEAD(&css->sibling);
INIT_LIST_HEAD(&css->children);
+ INIT_LIST_HEAD(&css->files);
css->serial_nr = css_serial_nr_next++;
if (cgroup_parent(cgrp)) {