[PATCH 2/5] cgroup: remove redundant get/put of task struct
From: Mandeep Singh Baines <hidden>
Date: 2011-12-20 23:15:31
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
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. Signed-off-by: Mandeep Singh Baines <redacted> Cc: Tejun Heo <redacted> Cc: Li Zefan <redacted> Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: KAMEZAWA Hiroyuki <redacted> Cc: Frederic Weisbecker <redacted> Cc: Oleg Nesterov <redacted> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Cc: Paul Menage <redacted> --- kernel/cgroup.c | 12 +----------- 1 files changed, 1 insertions(+), 11 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4166066..6649529 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c@@ -2130,7 +2130,6 @@ 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.
@@ -2152,7 +2151,7 @@ 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.
@@ -2233,12 +2232,6 @@ 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;
@@ -2287,14 +2280,12 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) cgroup_unlock(); return -EACCES; } - get_task_struct(tsk); rcu_read_unlock(); } else { if (threadgroup) tsk = current->group_leader; else tsk = current; - get_task_struct(tsk); } threadgroup_lock(tsk);
@@ -2306,7 +2297,6 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) threadgroup_unlock(tsk); - put_task_struct(tsk); cgroup_unlock(); return ret; }
--
1.7.3.1