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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2010-03-10 15:22:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-12 15:52:35 -0800
commit2468c7234b366eeb799ee0648cb58f9cba394a54 (patch)
tree050d7ea224b975eb71b05bf472f14f4c7bb13670 /kernel
parent5ce9f07bf1bed9a1f9886373ad0b149294f84c25 (diff)
cgroup: introduce cancel_attach()
Add cancel_attach() operation to struct cgroup_subsys. cancel_attach() can be used when can_attach() operation prepares something for the subsys, but we should rollback what can_attach() operation has prepared if attach task fails after we've succeeded in can_attach(). Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c40
1 files changed, 33 insertions, 7 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4fd90e12977..be45d2f6008 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1554,7 +1554,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
int retval = 0;
- struct cgroup_subsys *ss;
+ struct cgroup_subsys *ss, *failed_ss = NULL;
struct cgroup *oldcgrp;
struct css_set *cg;
struct css_set *newcg;
@@ -1568,8 +1568,16 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
for_each_subsys(root, ss) {
if (ss->can_attach) {
retval = ss->can_attach(ss, cgrp, tsk, false);
- if (retval)
- return retval;
+ if (retval) {
+ /*
+ * Remember on which subsystem the can_attach()
+ * failed, so that we only call cancel_attach()
+ * against the subsystems whose can_attach()
+ * succeeded. (See below)
+ */
+ failed_ss = ss;
+ goto out;
+ }
}
}
@@ -1583,14 +1591,17 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
*/
newcg = find_css_set(cg, cgrp);
put_css_set(cg);
- if (!newcg)
- return -ENOMEM;
+ if (!newcg) {
+ retval = -ENOMEM;
+ goto out;
+ }
task_lock(tsk);
if (tsk->flags & PF_EXITING) {
task_unlock(tsk);
put_css_set(newcg);
- return -ESRCH;
+ retval = -ESRCH;
+ goto out;
}
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1616,7 +1627,22 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
* is no longer empty.
*/
cgroup_wakeup_rmdir_waiter(cgrp);
- return 0;
+out:
+ if (retval) {
+ for_each_subsys(root, ss) {
+ if (ss == failed_ss)
+ /*
+ * This subsystem was the one that failed the
+ * can_attach() check earlier, so we don't need
+ * to call cancel_attach() against it or any
+ * remaining subsystems.
+ */
+ break;
+ if (ss->cancel_attach)
+ ss->cancel_attach(ss, cgrp, tsk, false);
+ }
+ }
+ return retval;
}
/*