threadgroup_lock() guarantees that the target threadgroup will remain stable - no new task will be added, no new PF_EXITING will be set and exec won't happen. Changes in V2: * https://lkml.org/lkml/2011/12/20/369 (Tejun Heo) * Undo incorrect removal of get/put from attach_task_by_pid() * Author * Remove a comment which is made stale by this change Signed-off-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Li Zefan <lizf@xxxxxxxxxxxxxx> Cc: containers@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: cgroups@xxxxxxxxxxxxxxx Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Paul Menage <paul@xxxxxxxxxxxxxx> --- kernel/cgroup.c | 11 ++--------- 1 files changed, 2 insertions(+), 9 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8228808..a85a700 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2116,7 +2116,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) retval = -EAGAIN; goto out_free_group_list; } - /* take a reference on each task in the group to go in the array. */ + tsk = leader; i = nr_migrating_tasks = 0; do { @@ -2128,7 +2128,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* as per above, nr_threads may decrease, but not increase. */ BUG_ON(i >= group_size); - get_task_struct(tsk); /* * saying GFP_ATOMIC has no effect here because we did prealloc * earlier, but it's good form to communicate our expectations. @@ -2150,7 +2149,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* methods shouldn't be called if no task is actually migrating */ retval = 0; if (!nr_migrating_tasks) - goto out_put_tasks; + goto out_free_group_list; /* * step 1: check that we can legitimately attach to the cgroup. @@ -2234,12 +2233,6 @@ out_cancel_attach: ss->cancel_attach(ss, cgrp, &tset); } } -out_put_tasks: - /* clean up the array of referenced threads in the group. */ - for (i = 0; i < group_size; i++) { - tc = flex_array_get(group, i); - put_task_struct(tc->task); - } out_free_group_list: flex_array_free(group); return retval; -- 1.7.3.1 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
