* [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set
[not found] ` <1324592816-13792-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
@ 2011-12-22 22:26 ` Mandeep Singh Baines
[not found] ` <1324592816-13792-2-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Mandeep Singh Baines @ 2011-12-22 22:26 UTC (permalink / raw)
To: Tejun Heo, Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Cc: Frederic Weisbecker, Mandeep Singh Baines, Oleg Nesterov,
Paul Menage, Tejun Heo, cgroups-u79uwXL29TY76Z2rM5mHXA,
Andrew Morton,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
In cgroup_attach_proc, we indirectly call find_existing_css_set 3
times. It is an expensive call so we want to call it a minimum
of times. This patch only calls it once and stores the result so
that it can be used later on when we call cgroup_task_migrate.
This required modifying cgroup_task_migrate to take the new css_set
(which we obtained from find_css_set) as a parameter. The nice side
effect of this is that cgroup_task_migrate is now identical for
cgroup_attach_task and cgroup_attach_proc. It also now returns a
void since it can never fail.
Changes in V3:
* https://lkml.org/lkml/2011/12/22/13 (Li Zefan)
* Fixed earlier bug by creating a seperate patch to remove tasklist_lock
Changes in V2:
* https://lkml.org/lkml/2011/12/20/372 (Tejun Heo)
* Move find_css_set call into loop which creates the flex array
* Author
* Kill css_set_refs and use group_size instead
* Fix an off-by-one error in counting css_set refs
* Add a retval check in out_list_teardown
Signed-off-by: Mandeep Singh Baines <msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Paul Menage <paul-inf54ven1CmVyaH7bEyXVA@public.gmane.org>
---
kernel/cgroup.c | 152 ++++++++++++-------------------------------------------
1 files changed, 32 insertions(+), 120 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 032139d..9eb486b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1763,6 +1763,7 @@ EXPORT_SYMBOL_GPL(cgroup_path);
struct task_and_cgroup {
struct task_struct *task;
struct cgroup *cgrp;
+ struct css_set *cg;
};
struct cgroup_taskset {
@@ -1843,11 +1844,10 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size);
* will already exist. If not set, this function might sleep, and can fail with
* -ENOMEM. Must be called with cgroup_mutex and threadgroup locked.
*/
-static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
- struct task_struct *tsk, bool guarantee)
+static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
+ struct task_struct *tsk, struct css_set *newcg)
{
struct css_set *oldcg;
- struct css_set *newcg;
/*
* We are synchronized through threadgroup_lock() against PF_EXITING
@@ -1857,23 +1857,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
WARN_ON_ONCE(tsk->flags & PF_EXITING);
oldcg = tsk->cgroups;
- /* locate or allocate a new css_set for this task. */
- if (guarantee) {
- /* we know the css_set we want already exists. */
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(oldcg, cgrp, template);
- BUG_ON(!newcg);
- get_css_set(newcg);
- read_unlock(&css_set_lock);
- } else {
- might_sleep();
- /* find_css_set will give us newcg already referenced. */
- newcg = find_css_set(oldcg, cgrp);
- if (!newcg)
- return -ENOMEM;
- }
-
task_lock(tsk);
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1892,7 +1875,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
put_css_set(oldcg);
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
- return 0;
}
/**
@@ -1910,6 +1892,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
struct cgroup *oldcgrp;
struct cgroupfs_root *root = cgrp->root;
struct cgroup_taskset tset = { };
+ struct css_set *newcg;
/* @tsk either already exited or can't exit until the end */
if (tsk->flags & PF_EXITING)
@@ -1939,9 +1922,13 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
}
- retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
- if (retval)
+ newcg = find_css_set(tsk->cgroups, cgrp);
+ if (!newcg) {
+ retval = -ENOMEM;
goto out;
+ }
+
+ cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);
for_each_subsys(root, ss) {
if (ss->attach)
@@ -1997,66 +1984,6 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-/*
- * cgroup_attach_proc works in two stages, the first of which prefetches all
- * new css_sets needed (to make sure we have enough memory before committing
- * to the move) and stores them in a list of entries of the following type.
- * TODO: possible optimization: use css_set->rcu_head for chaining instead
- */
-struct cg_list_entry {
- struct css_set *cg;
- struct list_head links;
-};
-
-static bool css_set_check_fetched(struct cgroup *cgrp,
- struct task_struct *tsk, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
-
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(cg, cgrp, template);
- read_unlock(&css_set_lock);
-
- /* doesn't exist at all? */
- if (!newcg)
- return false;
- /* see if it's already in the list */
- list_for_each_entry(cg_entry, newcg_list, links)
- if (cg_entry->cg == newcg)
- return true;
-
- /* not found */
- return false;
-}
-
-/*
- * Find the new css_set and store it in the list in preparation for moving the
- * given task to the given cgroup. Returns 0 or -ENOMEM.
- */
-static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
-
- /* ensure a new css_set will exist for this thread */
- newcg = find_css_set(cg, cgrp);
- if (!newcg)
- return -ENOMEM;
- /* add it to the list */
- cg_entry = kmalloc(sizeof(struct cg_list_entry), GFP_KERNEL);
- if (!cg_entry) {
- put_css_set(newcg);
- return -ENOMEM;
- }
- cg_entry->cg = newcg;
- list_add(&cg_entry->links, newcg_list);
- return 0;
-}
-
/**
* cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
* @cgrp: the cgroup to attach to
@@ -2070,20 +1997,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
int retval, i, group_size;
struct cgroup_subsys *ss, *failed_ss = NULL;
/* guaranteed to be initialized later, but the compiler needs this */
- struct css_set *oldcg;
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
struct task_struct *tsk;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
- /*
- * we need to make sure we have css_sets for all the tasks we're
- * going to move -before- we actually start moving them, so that in
- * case we get an ENOMEM we can bail out before making any changes.
- */
- struct list_head newcg_list;
- struct cg_list_entry *cg_entry, *temp_nobe;
/*
* step 0: in order to do expensive, possibly blocking operations for
@@ -2091,6 +2010,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
* rcu or tasklist locked. instead, build an array of all threads in the
* group - group_rwsem prevents new threads from appearing, and if
* threads exit, this will just be an over-estimate.
+ *
+ * While creating the list, also make sure css_sets exist for all
+ * threads to be migrated. we use find_css_set, which allocates a new
+ * one if necessary.
*/
group_size = get_nr_threads(leader);
/* flex_array supports very large thread-groups better than kmalloc. */
@@ -2122,6 +2045,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
/* nothing to do if this task is already in the cgroup */
if (ent.cgrp == cgrp)
continue;
+ ent.cg = find_css_set(tsk->cgroups, cgrp);
+ if (!ent.cg) {
+ retval = -ENOMEM;
+ group_size = i;
+ goto out_list_teardown;
+ }
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;
@@ -2134,7 +2063,7 @@ 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 (!group_size)
- goto out_free_group_list;
+ goto out_list_teardown;
/*
* step 1: check that we can legitimately attach to the cgroup.
@@ -2150,34 +2079,18 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
/*
- * step 2: make sure css_sets exist for all threads to be migrated.
- * we use find_css_set, which allocates a new one if necessary.
- */
- INIT_LIST_HEAD(&newcg_list);
- for (i = 0; i < group_size; i++) {
- tc = flex_array_get(group, i);
- oldcg = tc->task->cgroups;
-
- /* if we don't already have it in the list get a new one */
- if (!css_set_check_fetched(cgrp, tc->task, oldcg, &newcg_list))
- if (retval = css_set_prefetch(cgrp, oldcg, &newcg_list))
- goto out_list_teardown;
- }
-
- /*
- * step 3: now that we're guaranteed success wrt the css_sets,
+ * step 2: now that we're guaranteed success wrt the css_sets,
* proceed to move all tasks to the new cgroup. There are no
* failure cases after here, so this is the commit point.
*/
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- retval = cgroup_task_migrate(cgrp, tc->cgrp, tc->task, true);
- BUG_ON(retval);
+ cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg);
}
/* nothing is sensitive to fork() after this point. */
/*
- * step 4: do subsystem attach callbacks.
+ * step 3: do subsystem attach callbacks.
*/
for_each_subsys(root, ss) {
if (ss->attach)
@@ -2185,20 +2098,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
/*
- * step 5: success! and cleanup
+ * step 4: success! and cleanup
*/
synchronize_rcu();
cgroup_wakeup_rmdir_waiter(cgrp);
retval = 0;
-out_list_teardown:
- /* clean up the list of prefetched css_sets. */
- list_for_each_entry_safe(cg_entry, temp_nobe, &newcg_list, links) {
- list_del(&cg_entry->links);
- put_css_set(cg_entry->cg);
- kfree(cg_entry);
- }
out_cancel_attach:
- /* same deal as in cgroup_attach_task */
if (retval) {
for_each_subsys(root, ss) {
if (ss == failed_ss)
@@ -2207,6 +2112,13 @@ out_cancel_attach:
ss->cancel_attach(ss, cgrp, &tset);
}
}
+out_list_teardown:
+ if (retval) {
+ for (i = 0; i < group_size; i++) {
+ tc = flex_array_get(group, i);
+ put_css_set(tc->cg);
+ }
+ }
out_free_group_list:
flex_array_free(group);
return retval;
--
1.7.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set
[not found] ` <1324592816-13792-2-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
@ 2011-12-22 23:12 ` Tejun Heo
[not found] ` <20111222231203.GO17084-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Tejun Heo @ 2011-12-22 23:12 UTC (permalink / raw)
To: Mandeep Singh Baines
Cc: Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA,
cgroups-u79uwXL29TY76Z2rM5mHXA, KAMEZAWA Hiroyuki, Oleg Nesterov,
Andrew Morton, Paul Menage
On Thu, Dec 22, 2011 at 02:26:56PM -0800, Mandeep Singh Baines wrote:
> +out_list_teardown:
> + if (retval) {
> + for (i = 0; i < group_size; i++) {
> + tc = flex_array_get(group, i);
> + put_css_set(tc->cg);
> + }
> + }
Don't we need to put them even after success?
--
tejun
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set
[not found] ` <20111222231203.GO17084-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
@ 2011-12-23 0:29 ` Mandeep Singh Baines
0 siblings, 0 replies; 6+ messages in thread
From: Mandeep Singh Baines @ 2011-12-23 0:29 UTC (permalink / raw)
To: Tejun Heo
Cc: Mandeep Singh Baines, Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA,
cgroups-u79uwXL29TY76Z2rM5mHXA, KAMEZAWA Hiroyuki, Oleg Nesterov,
Andrew Morton, Paul Menage
Tejun Heo (tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org) wrote:
> On Thu, Dec 22, 2011 at 02:26:56PM -0800, Mandeep Singh Baines wrote:
> > +out_list_teardown:
> > + if (retval) {
> > + for (i = 0; i < group_size; i++) {
> > + tc = flex_array_get(group, i);
> > + put_css_set(tc->cg);
> > + }
> > + }
>
> Don't we need to put them even after success?
>
On success, we need to keep a reference for each thread in the threadgroup.
> --
> tejun
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] cgroup: remove tasklist_lock from cgroup_attach_proc
@ 2011-12-23 2:52 Mandeep Singh Baines
[not found] ` <1324608750-13313-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Mandeep Singh Baines @ 2011-12-23 2:52 UTC (permalink / raw)
To: Tejun Heo, Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Cc: Mandeep Singh Baines, Oleg Nesterov, Paul Menage, Tejun Heo,
cgroups-u79uwXL29TY76Z2rM5mHXA, Andrew Morton,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
Since cgroup_attach_proc is protected by a threadgroup_lock, we
no longer need a tasklist_lock to protect while_each_thread.
To keep the complexity of the double-check locking in one place,
I also moved the thread_group_leader check up into
attach_task_by_pid. This allows us to use a goto instead of
returning -EAGAIN.
While at it, also converted a couple of returns to gotos.
Changes in V2:
* https://lkml.org/lkml/2011/12/22/86 (Tejun Heo)
* Use a goto instead of returning -EAGAIN
Suggested-by: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mandeep Singh Baines <msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Paul Menage <paul-inf54ven1CmVyaH7bEyXVA@public.gmane.org>
---
kernel/cgroup.c | 72 ++++++++++++++++++------------------------------------
1 files changed, 24 insertions(+), 48 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1042b3c..625526b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2102,21 +2102,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
if (retval)
goto out_free_group_list;
- /* prevent changes to the threadgroup list while we take a snapshot. */
- read_lock(&tasklist_lock);
- if (!thread_group_leader(leader)) {
- /*
- * a race with de_thread from another thread's exec() may strip
- * us of our leadership, making while_each_thread unsafe to use
- * on this task. if this happens, there is no choice but to
- * throw this task away and try again (from cgroup_procs_write);
- * this is "double-double-toil-and-trouble-check locking".
- */
- read_unlock(&tasklist_lock);
- retval = -EAGAIN;
- goto out_free_group_list;
- }
-
tsk = leader;
i = 0;
do {
@@ -2145,7 +2130,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
group_size = i;
tset.tc_array = group;
tset.tc_array_len = group_size;
- read_unlock(&tasklist_lock);
/* methods shouldn't be called if no task is actually migrating */
retval = 0;
@@ -2242,22 +2226,14 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
+retry_find_task:
if (pid) {
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (!tsk) {
rcu_read_unlock();
- cgroup_unlock();
- return -ESRCH;
- }
- if (threadgroup) {
- /*
- * RCU protects this access, since tsk was found in the
- * tid map. a race with de_thread may cause group_leader
- * to stop being the leader, but cgroup_attach_proc will
- * detect it later.
- */
- tsk = tsk->group_leader;
+ ret= -ESRCH;
+ goto out_unlock_cgroup;
}
/*
* even if we're attaching all tasks in the thread group, we
@@ -2268,29 +2244,38 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
cred->euid != tcred->uid &&
cred->euid != tcred->suid) {
rcu_read_unlock();
- cgroup_unlock();
- return -EACCES;
+ ret = -EACCES;
+ goto out_unlock_cgroup;
}
get_task_struct(tsk);
rcu_read_unlock();
} else {
- if (threadgroup)
- tsk = current->group_leader;
- else
- tsk = current;
+ tsk = current;
get_task_struct(tsk);
}
threadgroup_lock(tsk);
-
- if (threadgroup)
- ret = cgroup_attach_proc(cgrp, tsk);
- else
+ if (threadgroup) {
+ struct task_struct *leader = tsk->group_leader;
+ if (!thread_group_leader(leader)) {
+ /*
+ * a race with de_thread from another thread's exec()
+ * may strip us of our leadership, if this happens,
+ * there is no choice but to throw this task away and
+ * try again; this is
+ * "double-double-toil-and-trouble-check locking".
+ */
+ threadgroup_unlock(tsk);
+ put_task_struct(tsk);
+ goto retry_find_task;
+ }
+ ret = cgroup_attach_proc(cgrp, leader);
+ } else
ret = cgroup_attach_task(cgrp, tsk);
-
threadgroup_unlock(tsk);
put_task_struct(tsk);
+out_unlock_cgroup:
cgroup_unlock();
return ret;
}
@@ -2302,16 +2287,7 @@ static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid)
{
- int ret;
- do {
- /*
- * attach_proc fails with -EAGAIN if threadgroup leadership
- * changes in the middle of the operation, in which case we need
- * to find the task_struct for the new leader and start over.
- */
- ret = attach_task_by_pid(cgrp, tgid, true);
- } while (ret == -EAGAIN);
- return ret;
+ return attach_task_by_pid(cgrp, tgid, true);
}
/**
--
1.7.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set
[not found] ` <1324608750-13313-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
@ 2011-12-23 2:52 ` Mandeep Singh Baines
0 siblings, 0 replies; 6+ messages in thread
From: Mandeep Singh Baines @ 2011-12-23 2:52 UTC (permalink / raw)
To: Tejun Heo, Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Cc: Frederic Weisbecker, Mandeep Singh Baines, Oleg Nesterov,
Paul Menage, Tejun Heo, cgroups-u79uwXL29TY76Z2rM5mHXA,
Andrew Morton,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
In cgroup_attach_proc, we indirectly call find_existing_css_set 3
times. It is an expensive call so we want to call it a minimum
of times. This patch only calls it once and stores the result so
that it can be used later on when we call cgroup_task_migrate.
This required modifying cgroup_task_migrate to take the new css_set
(which we obtained from find_css_set) as a parameter. The nice side
effect of this is that cgroup_task_migrate is now identical for
cgroup_attach_task and cgroup_attach_proc. It also now returns a
void since it can never fail.
Changes in V3:
* https://lkml.org/lkml/2011/12/22/13 (Li Zefan)
* Fixed earlier bug by creating a seperate patch to remove tasklist_lock
Changes in V2:
* https://lkml.org/lkml/2011/12/20/372 (Tejun Heo)
* Move find_css_set call into loop which creates the flex array
* Author
* Kill css_set_refs and use group_size instead
* Fix an off-by-one error in counting css_set refs
* Add a retval check in out_list_teardown
Signed-off-by: Mandeep Singh Baines <msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Paul Menage <paul-inf54ven1CmVyaH7bEyXVA@public.gmane.org>
---
kernel/cgroup.c | 152 ++++++++++++-------------------------------------------
1 files changed, 32 insertions(+), 120 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 625526b..d1612df 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1763,6 +1763,7 @@ EXPORT_SYMBOL_GPL(cgroup_path);
struct task_and_cgroup {
struct task_struct *task;
struct cgroup *cgrp;
+ struct css_set *cg;
};
struct cgroup_taskset {
@@ -1843,11 +1844,10 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size);
* will already exist. If not set, this function might sleep, and can fail with
* -ENOMEM. Must be called with cgroup_mutex and threadgroup locked.
*/
-static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
- struct task_struct *tsk, bool guarantee)
+static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
+ struct task_struct *tsk, struct css_set *newcg)
{
struct css_set *oldcg;
- struct css_set *newcg;
/*
* We are synchronized through threadgroup_lock() against PF_EXITING
@@ -1857,23 +1857,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
WARN_ON_ONCE(tsk->flags & PF_EXITING);
oldcg = tsk->cgroups;
- /* locate or allocate a new css_set for this task. */
- if (guarantee) {
- /* we know the css_set we want already exists. */
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(oldcg, cgrp, template);
- BUG_ON(!newcg);
- get_css_set(newcg);
- read_unlock(&css_set_lock);
- } else {
- might_sleep();
- /* find_css_set will give us newcg already referenced. */
- newcg = find_css_set(oldcg, cgrp);
- if (!newcg)
- return -ENOMEM;
- }
-
task_lock(tsk);
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1892,7 +1875,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
put_css_set(oldcg);
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
- return 0;
}
/**
@@ -1910,6 +1892,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
struct cgroup *oldcgrp;
struct cgroupfs_root *root = cgrp->root;
struct cgroup_taskset tset = { };
+ struct css_set *newcg;
/* @tsk either already exited or can't exit until the end */
if (tsk->flags & PF_EXITING)
@@ -1939,9 +1922,13 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
}
- retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
- if (retval)
+ newcg = find_css_set(tsk->cgroups, cgrp);
+ if (!newcg) {
+ retval = -ENOMEM;
goto out;
+ }
+
+ cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);
for_each_subsys(root, ss) {
if (ss->attach)
@@ -1997,66 +1984,6 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-/*
- * cgroup_attach_proc works in two stages, the first of which prefetches all
- * new css_sets needed (to make sure we have enough memory before committing
- * to the move) and stores them in a list of entries of the following type.
- * TODO: possible optimization: use css_set->rcu_head for chaining instead
- */
-struct cg_list_entry {
- struct css_set *cg;
- struct list_head links;
-};
-
-static bool css_set_check_fetched(struct cgroup *cgrp,
- struct task_struct *tsk, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
-
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(cg, cgrp, template);
- read_unlock(&css_set_lock);
-
- /* doesn't exist at all? */
- if (!newcg)
- return false;
- /* see if it's already in the list */
- list_for_each_entry(cg_entry, newcg_list, links)
- if (cg_entry->cg == newcg)
- return true;
-
- /* not found */
- return false;
-}
-
-/*
- * Find the new css_set and store it in the list in preparation for moving the
- * given task to the given cgroup. Returns 0 or -ENOMEM.
- */
-static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
-
- /* ensure a new css_set will exist for this thread */
- newcg = find_css_set(cg, cgrp);
- if (!newcg)
- return -ENOMEM;
- /* add it to the list */
- cg_entry = kmalloc(sizeof(struct cg_list_entry), GFP_KERNEL);
- if (!cg_entry) {
- put_css_set(newcg);
- return -ENOMEM;
- }
- cg_entry->cg = newcg;
- list_add(&cg_entry->links, newcg_list);
- return 0;
-}
-
/**
* cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
* @cgrp: the cgroup to attach to
@@ -2070,20 +1997,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
int retval, i, group_size;
struct cgroup_subsys *ss, *failed_ss = NULL;
/* guaranteed to be initialized later, but the compiler needs this */
- struct css_set *oldcg;
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
struct task_struct *tsk;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
- /*
- * we need to make sure we have css_sets for all the tasks we're
- * going to move -before- we actually start moving them, so that in
- * case we get an ENOMEM we can bail out before making any changes.
- */
- struct list_head newcg_list;
- struct cg_list_entry *cg_entry, *temp_nobe;
/*
* step 0: in order to do expensive, possibly blocking operations for
@@ -2091,6 +2010,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
* rcu or tasklist locked. instead, build an array of all threads in the
* group - group_rwsem prevents new threads from appearing, and if
* threads exit, this will just be an over-estimate.
+ *
+ * While creating the list, also make sure css_sets exist for all
+ * threads to be migrated. we use find_css_set, which allocates a new
+ * one if necessary.
*/
group_size = get_nr_threads(leader);
/* flex_array supports very large thread-groups better than kmalloc. */
@@ -2122,6 +2045,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
/* nothing to do if this task is already in the cgroup */
if (ent.cgrp == cgrp)
continue;
+ ent.cg = find_css_set(tsk->cgroups, cgrp);
+ if (!ent.cg) {
+ retval = -ENOMEM;
+ group_size = i;
+ goto out_list_teardown;
+ }
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;
@@ -2134,7 +2063,7 @@ 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 (!group_size)
- goto out_free_group_list;
+ goto out_list_teardown;
/*
* step 1: check that we can legitimately attach to the cgroup.
@@ -2150,34 +2079,18 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
/*
- * step 2: make sure css_sets exist for all threads to be migrated.
- * we use find_css_set, which allocates a new one if necessary.
- */
- INIT_LIST_HEAD(&newcg_list);
- for (i = 0; i < group_size; i++) {
- tc = flex_array_get(group, i);
- oldcg = tc->task->cgroups;
-
- /* if we don't already have it in the list get a new one */
- if (!css_set_check_fetched(cgrp, tc->task, oldcg, &newcg_list))
- if (retval = css_set_prefetch(cgrp, oldcg, &newcg_list))
- goto out_list_teardown;
- }
-
- /*
- * step 3: now that we're guaranteed success wrt the css_sets,
+ * step 2: now that we're guaranteed success wrt the css_sets,
* proceed to move all tasks to the new cgroup. There are no
* failure cases after here, so this is the commit point.
*/
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- retval = cgroup_task_migrate(cgrp, tc->cgrp, tc->task, true);
- BUG_ON(retval);
+ cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg);
}
/* nothing is sensitive to fork() after this point. */
/*
- * step 4: do subsystem attach callbacks.
+ * step 3: do subsystem attach callbacks.
*/
for_each_subsys(root, ss) {
if (ss->attach)
@@ -2185,20 +2098,12 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
/*
- * step 5: success! and cleanup
+ * step 4: success! and cleanup
*/
synchronize_rcu();
cgroup_wakeup_rmdir_waiter(cgrp);
retval = 0;
-out_list_teardown:
- /* clean up the list of prefetched css_sets. */
- list_for_each_entry_safe(cg_entry, temp_nobe, &newcg_list, links) {
- list_del(&cg_entry->links);
- put_css_set(cg_entry->cg);
- kfree(cg_entry);
- }
out_cancel_attach:
- /* same deal as in cgroup_attach_task */
if (retval) {
for_each_subsys(root, ss) {
if (ss == failed_ss)
@@ -2207,6 +2112,13 @@ out_cancel_attach:
ss->cancel_attach(ss, cgrp, &tset);
}
}
+out_list_teardown:
+ if (retval) {
+ for (i = 0; i < group_size; i++) {
+ tc = flex_array_get(group, i);
+ put_css_set(tc->cg);
+ }
+ }
out_free_group_list:
flex_array_free(group);
return retval;
--
1.7.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set
[not found] ` <1324661325-31968-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
@ 2011-12-23 17:28 ` Mandeep Singh Baines
0 siblings, 0 replies; 6+ messages in thread
From: Mandeep Singh Baines @ 2011-12-23 17:28 UTC (permalink / raw)
To: Tejun Heo, Li Zefan, Frederic Weisbecker,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Cc: Frederic Weisbecker, Mandeep Singh Baines, Oleg Nesterov,
Paul Menage, Tejun Heo, cgroups-u79uwXL29TY76Z2rM5mHXA,
Andrew Morton,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
In cgroup_attach_proc, we indirectly call find_existing_css_set 3
times. It is an expensive call so we want to call it a minimum
of times. This patch only calls it once and stores the result so
that it can be used later on when we call cgroup_task_migrate.
This required modifying cgroup_task_migrate to take the new css_set
(which we obtained from find_css_set) as a parameter. The nice side
effect of this is that cgroup_task_migrate is now identical for
cgroup_attach_task and cgroup_attach_proc. It also now returns a
void since it can never fail.
Changes in V4:
* https://lkml.org/lkml/2011/12/22/421 (Li Zefan)
* Avoid GFP_KERNEL (sleep) in rcu_read_lock by getting css_set in
a separate loop not under an rcu_read_lock
Changes in V3:
* https://lkml.org/lkml/2011/12/22/13 (Li Zefan)
* Fixed earlier bug by creating a seperate patch to remove tasklist_lock
Changes in V2:
* https://lkml.org/lkml/2011/12/20/372 (Tejun Heo)
* Move find_css_set call into loop which creates the flex array
* Author
* Kill css_set_refs and use group_size instead
* Fix an off-by-one error in counting css_set refs
* Add a retval check in out_list_teardown
Signed-off-by: Mandeep Singh Baines <msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
Cc: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: Paul Menage <paul-inf54ven1CmVyaH7bEyXVA@public.gmane.org>
---
kernel/cgroup.c | 142 +++++++++++-------------------------------------------
1 files changed, 29 insertions(+), 113 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 6ee1438..4823d40 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1763,6 +1763,7 @@ EXPORT_SYMBOL_GPL(cgroup_path);
struct task_and_cgroup {
struct task_struct *task;
struct cgroup *cgrp;
+ struct css_set *cg;
};
struct cgroup_taskset {
@@ -1843,11 +1844,10 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size);
* will already exist. If not set, this function might sleep, and can fail with
* -ENOMEM. Must be called with cgroup_mutex and threadgroup locked.
*/
-static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
- struct task_struct *tsk, bool guarantee)
+static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
+ struct task_struct *tsk, struct css_set *newcg)
{
struct css_set *oldcg;
- struct css_set *newcg;
/*
* We are synchronized through threadgroup_lock() against PF_EXITING
@@ -1857,23 +1857,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
WARN_ON_ONCE(tsk->flags & PF_EXITING);
oldcg = tsk->cgroups;
- /* locate or allocate a new css_set for this task. */
- if (guarantee) {
- /* we know the css_set we want already exists. */
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(oldcg, cgrp, template);
- BUG_ON(!newcg);
- get_css_set(newcg);
- read_unlock(&css_set_lock);
- } else {
- might_sleep();
- /* find_css_set will give us newcg already referenced. */
- newcg = find_css_set(oldcg, cgrp);
- if (!newcg)
- return -ENOMEM;
- }
-
task_lock(tsk);
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1892,7 +1875,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
put_css_set(oldcg);
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
- return 0;
}
/**
@@ -1910,6 +1892,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
struct cgroup *oldcgrp;
struct cgroupfs_root *root = cgrp->root;
struct cgroup_taskset tset = { };
+ struct css_set *newcg;
/* @tsk either already exited or can't exit until the end */
if (tsk->flags & PF_EXITING)
@@ -1939,9 +1922,13 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
}
- retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
- if (retval)
+ newcg = find_css_set(tsk->cgroups, cgrp);
+ if (!newcg) {
+ retval = -ENOMEM;
goto out;
+ }
+
+ cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);
for_each_subsys(root, ss) {
if (ss->attach)
@@ -1997,66 +1984,6 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-/*
- * cgroup_attach_proc works in two stages, the first of which prefetches all
- * new css_sets needed (to make sure we have enough memory before committing
- * to the move) and stores them in a list of entries of the following type.
- * TODO: possible optimization: use css_set->rcu_head for chaining instead
- */
-struct cg_list_entry {
- struct css_set *cg;
- struct list_head links;
-};
-
-static bool css_set_check_fetched(struct cgroup *cgrp,
- struct task_struct *tsk, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
-
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(cg, cgrp, template);
- read_unlock(&css_set_lock);
-
- /* doesn't exist at all? */
- if (!newcg)
- return false;
- /* see if it's already in the list */
- list_for_each_entry(cg_entry, newcg_list, links)
- if (cg_entry->cg == newcg)
- return true;
-
- /* not found */
- return false;
-}
-
-/*
- * Find the new css_set and store it in the list in preparation for moving the
- * given task to the given cgroup. Returns 0 or -ENOMEM.
- */
-static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
-
- /* ensure a new css_set will exist for this thread */
- newcg = find_css_set(cg, cgrp);
- if (!newcg)
- return -ENOMEM;
- /* add it to the list */
- cg_entry = kmalloc(sizeof(struct cg_list_entry), GFP_KERNEL);
- if (!cg_entry) {
- put_css_set(newcg);
- return -ENOMEM;
- }
- cg_entry->cg = newcg;
- list_add(&cg_entry->links, newcg_list);
- return 0;
-}
-
/**
* cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
* @cgrp: the cgroup to attach to
@@ -2067,23 +1994,15 @@ static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
*/
int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
{
- int retval, i, group_size;
+ int retval, i, group_size, css_set_refs = 0;
struct cgroup_subsys *ss, *failed_ss = NULL;
/* guaranteed to be initialized later, but the compiler needs this */
- struct css_set *oldcg;
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
struct task_struct *tsk;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
- /*
- * we need to make sure we have css_sets for all the tasks we're
- * going to move -before- we actually start moving them, so that in
- * case we get an ENOMEM we can bail out before making any changes.
- */
- struct list_head newcg_list;
- struct cg_list_entry *cg_entry, *temp_nobe;
/*
* step 0: in order to do expensive, possibly blocking operations for
@@ -2114,15 +2033,15 @@ 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);
- /*
- * saying GFP_ATOMIC has no effect here because we did prealloc
- * earlier, but it's good form to communicate our expectations.
- */
ent.task = tsk;
ent.cgrp = task_cgroup_from_root(tsk, root);
/* nothing to do if this task is already in the cgroup */
if (ent.cgrp == cgrp)
continue;
+ /*
+ * saying GFP_ATOMIC has no effect here because we did prealloc
+ * earlier, but it's good form to communicate our expectations.
+ */
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;
@@ -2151,19 +2070,18 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
}
}
- /*
+ /*
* step 2: make sure css_sets exist for all threads to be migrated.
* we use find_css_set, which allocates a new one if necessary.
*/
- INIT_LIST_HEAD(&newcg_list);
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- oldcg = tc->task->cgroups;
-
- /* if we don't already have it in the list get a new one */
- if (!css_set_check_fetched(cgrp, tc->task, oldcg, &newcg_list))
- if (retval = css_set_prefetch(cgrp, oldcg, &newcg_list))
- goto out_list_teardown;
+ tc->cg = find_css_set(tc->task->cgroups, cgrp);
+ if (!tc->cg) {
+ retval = -ENOMEM;
+ css_set_refs = i;
+ goto out_put_css_set_refs;
+ }
}
/*
@@ -2173,8 +2091,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
*/
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- retval = cgroup_task_migrate(cgrp, tc->cgrp, tc->task, true);
- BUG_ON(retval);
+ cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg);
}
/* nothing is sensitive to fork() after this point. */
@@ -2192,15 +2109,14 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
synchronize_rcu();
cgroup_wakeup_rmdir_waiter(cgrp);
retval = 0;
-out_list_teardown:
- /* clean up the list of prefetched css_sets. */
- list_for_each_entry_safe(cg_entry, temp_nobe, &newcg_list, links) {
- list_del(&cg_entry->links);
- put_css_set(cg_entry->cg);
- kfree(cg_entry);
+out_put_css_set_refs:
+ if (retval) {
+ for (i = 0; i < css_set_refs; i++) {
+ tc = flex_array_get(group, i);
+ put_css_set(tc->cg);
+ }
}
out_cancel_attach:
- /* same deal as in cgroup_attach_task */
if (retval) {
for_each_subsys(root, ss) {
if (ss == failed_ss)
--
1.7.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-12-23 17:28 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-12-23 2:52 [PATCH 1/2] cgroup: remove tasklist_lock from cgroup_attach_proc Mandeep Singh Baines
[not found] ` <1324608750-13313-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-12-23 2:52 ` [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set Mandeep Singh Baines
-- strict thread matches above, loose matches on Subject: below --
2011-12-23 17:28 [PATCH 1/2] cgroup: replace tasklist_lock with rcu_read_lock Mandeep Singh Baines
[not found] ` <1324661325-31968-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-12-23 17:28 ` [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set Mandeep Singh Baines
2011-12-22 22:26 [PATCH 1/2] cgroup: remove tasklist_lock from cgroup_attach_proc Mandeep Singh Baines
[not found] ` <1324592816-13792-1-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-12-22 22:26 ` [PATCH 2/2] cgroup: remove extra calls to find_existing_css_set Mandeep Singh Baines
[not found] ` <1324592816-13792-2-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2011-12-22 23:12 ` Tejun Heo
[not found] ` <20111222231203.GO17084-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2011-12-23 0:29 ` Mandeep Singh Baines
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).