diff options
| author | Paul Menage <menage@google.com> | 2008-02-07 00:13:45 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-07 08:42:18 -0800 |
| commit | 8dc4f3e17dd5f7e59ce568155ccd8974af879315 (patch) | |
| tree | 959b1197fea798c9daae4dd6c9596ab710d41fda /Documentation | |
| parent | 622d42cac9ed42098aa50c53994f625abfa3d473 (diff) | |
cgroups: move cgroups destroy() callbacks to cgroup_diput()
Move the calls to the cgroup subsystem destroy() methods from
cgroup_rmdir() to cgroup_diput(). This allows control file reads and
writes to access their subsystem state without having to be concerned with
locking against cgroup destruction - the control file dentry will keep the
cgroup and its subsystem state objects alive until the file is closed.
The documentation is updated to reflect the changed semantics of destroy();
additionally the locking comments for destroy() and some other methods were
clarified and decrustified.
Signed-off-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/cgroups.txt | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt index 98a26f81fa75..42d7c4cb39cd 100644 --- a/Documentation/cgroups.txt +++ b/Documentation/cgroups.txt @@ -456,7 +456,7 @@ methods are create/destroy. Any others that are null are presumed to be successful no-ops. struct cgroup_subsys_state *create(struct cgroup *cont) -LL=cgroup_mutex +(cgroup_mutex held by caller) Called to create a subsystem state object for a cgroup. The subsystem should allocate its subsystem state object for the passed @@ -471,14 +471,19 @@ it's the root of the hierarchy) and may be an appropriate place for initialization code. void destroy(struct cgroup *cont) -LL=cgroup_mutex +(cgroup_mutex held by caller) -The cgroup system is about to destroy the passed cgroup; the -subsystem should do any necessary cleanup +The cgroup system is about to destroy the passed cgroup; the subsystem +should do any necessary cleanup and free its subsystem state +object. By the time this method is called, the cgroup has already been +unlinked from the file system and from the child list of its parent; +cgroup->parent is still valid. (Note - can also be called for a +newly-created cgroup if an error occurs after this subsystem's +create() method has been called for the new cgroup). int can_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct task_struct *task) -LL=cgroup_mutex +(cgroup_mutex held by caller) Called prior to moving a task into a cgroup; if the subsystem returns an error, this will abort the attach operation. If a NULL @@ -489,25 +494,20 @@ remain valid while the caller holds cgroup_mutex. void attach(struct cgroup_subsys *ss, struct cgroup *cont, struct cgroup *old_cont, struct task_struct *task) -LL=cgroup_mutex - Called after the task has been attached to the cgroup, to allow any post-attachment activity that requires memory allocations or blocking. void fork(struct cgroup_subsy *ss, struct task_struct *task) -LL=callback_mutex, maybe read_lock(tasklist_lock) Called when a task is forked into a cgroup. Also called during registration for all existing tasks. void exit(struct cgroup_subsys *ss, struct task_struct *task) -LL=callback_mutex Called during task exit int populate(struct cgroup_subsys *ss, struct cgroup *cont) -LL=none Called after creation of a cgroup to allow a subsystem to populate the cgroup directory with file entries. The subsystem should make @@ -524,7 +524,7 @@ example in cpusets, no task may attach before 'cpus' and 'mems' are set up. void bind(struct cgroup_subsys *ss, struct cgroup *root) -LL=callback_mutex +(cgroup_mutex held by caller) Called when a cgroup subsystem is rebound to a different hierarchy and root cgroup. Currently this will only involve movement between |