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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 /include/linux/cgroup.h
parent4df8dc903161c03cd9bff9077d8427fefe808e6d (diff)
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 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 355bf2ed8867..fb717f2cba5b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -490,6 +490,19 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
pr_cont_kernfs_path(cgrp->kn);
}
+/**
+ * cgroup_file_notify - generate a file modified event for a cgroup_file
+ * @cfile: target cgroup_file
+ *
+ * @cfile must have been obtained by setting cftype->file_offset.
+ */
+static inline void cgroup_file_notify(struct cgroup_file *cfile)
+{
+ /* might not have been created due to one of the CFTYPE selector flags */
+ if (cfile->kn)
+ kernfs_notify(cfile->kn);
+}
+
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;