From f780bdb7c1c73009cb57adcf99ef50027d80bf3c Mon Sep 17 00:00:00 2001 From: Ben Blum Date: Thu, 26 May 2011 16:25:19 -0700 Subject: cgroups: add per-thread subsystem callbacks Add cgroup subsystem callbacks for per-thread attachment in atomic contexts Add can_attach_task(), pre_attach(), and attach_task() as new callbacks for cgroups's subsystem interface. Unlike can_attach and attach, these are for per-thread operations, to be called potentially many times when attaching an entire threadgroup. Also, the old "bool threadgroup" interface is removed, as replaced by this. All subsystems are modified for the new interface - of note is cpuset, which requires from/to nodemasks for attach to be globally scoped (though per-cpuset would work too) to persist from its pre_attach to attach_task and attach. This is a pre-patch for cgroup-procs-writable.patch. Signed-off-by: Ben Blum Cc: "Eric W. Biederman" Cc: Li Zefan Cc: Matt Helsley Reviewed-by: Paul Menage Cc: Oleg Nesterov Cc: David Rientjes Cc: Miao Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cgroups/cgroups.txt | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) (limited to 'Documentation') diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index aedf1bd02fdd..b3bd3bdbe202 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -575,7 +575,7 @@ rmdir() will fail with it. From this behavior, pre_destroy() can be called multiple times against a cgroup. int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, - struct task_struct *task, bool threadgroup) + struct task_struct *task) (cgroup_mutex held by caller) Called prior to moving a task into a cgroup; if the subsystem @@ -584,9 +584,14 @@ task is passed, then a successful result indicates that *any* unspecified task can be moved into the cgroup. Note that this isn't called on a fork. If this method returns 0 (success) then this should remain valid while the caller holds cgroup_mutex and it is ensured that either -attach() or cancel_attach() will be called in future. If threadgroup is -true, then a successful result indicates that all threads in the given -thread's threadgroup can be moved together. +attach() or cancel_attach() will be called in future. + +int can_attach_task(struct cgroup *cgrp, struct task_struct *tsk); +(cgroup_mutex held by caller) + +As can_attach, but for operations that must be run once per task to be +attached (possibly many when using cgroup_attach_proc). Called after +can_attach. void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *task, bool threadgroup) @@ -598,15 +603,24 @@ function, so that the subsystem can implement a rollback. If not, not necessary. This will be called only about subsystems whose can_attach() operation have succeeded. +void pre_attach(struct cgroup *cgrp); +(cgroup_mutex held by caller) + +For any non-per-thread attachment work that needs to happen before +attach_task. Needed by cpuset. + void attach(struct cgroup_subsys *ss, struct cgroup *cgrp, - struct cgroup *old_cgrp, struct task_struct *task, - bool threadgroup) + struct cgroup *old_cgrp, struct task_struct *task) (cgroup_mutex held by caller) Called after the task has been attached to the cgroup, to allow any post-attachment activity that requires memory allocations or blocking. -If threadgroup is true, the subsystem should take care of all threads -in the specified thread's threadgroup. Currently does not support any + +void attach_task(struct cgroup *cgrp, struct task_struct *tsk); +(cgroup_mutex held by caller) + +As attach, but for operations that must be run once per task to be attached, +like can_attach_task. Called before attach. Currently does not support any subsystem that might need the old_cgrp for every thread in the group. void fork(struct cgroup_subsy *ss, struct task_struct *task) -- cgit v1.2.1