* [PATCH] cgroups: remove rcu_read_lock() in cgroupstats_build()
@ 2008-11-22 4:09 Lai Jiangshan
2008-11-24 20:41 ` Paul Menage
0 siblings, 1 reply; 2+ messages in thread
From: Lai Jiangshan @ 2008-11-22 4:09 UTC (permalink / raw)
To: Andrew Morton, Paul Menage, Linux Kernel Mailing List
cgroup_iter_* do not need rcu_read_lock().
In cgroup_enable_task_cg_lists(), do_each_thread() and
while_each_thread() are protected by RCU,
it's OK, for write_lock(&css_set_lock) implies rcu_read_lock() in non-RT kernel.
If we need explicit rcu_read_lock(), we should add rcu_read_lock()
in cgroup_enable_task_cg_lists(), not cgroup_iter_*.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 358e775..e6d92a5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2047,7 +2047,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
ret = 0;
cgrp = dentry->d_fsdata;
- rcu_read_lock();
cgroup_iter_start(cgrp, &it);
while ((tsk = cgroup_iter_next(cgrp, &it))) {
@@ -2072,7 +2071,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
}
cgroup_iter_end(cgrp, &it);
- rcu_read_unlock();
err:
return ret;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] cgroups: remove rcu_read_lock() in cgroupstats_build()
2008-11-22 4:09 [PATCH] cgroups: remove rcu_read_lock() in cgroupstats_build() Lai Jiangshan
@ 2008-11-24 20:41 ` Paul Menage
0 siblings, 0 replies; 2+ messages in thread
From: Paul Menage @ 2008-11-24 20:41 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Andrew Morton, Linux Kernel Mailing List
On Fri, Nov 21, 2008 at 8:09 PM, Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
>
> cgroup_iter_* do not need rcu_read_lock().
>
> In cgroup_enable_task_cg_lists(), do_each_thread() and
> while_each_thread() are protected by RCU,
> it's OK, for write_lock(&css_set_lock) implies rcu_read_lock() in non-RT kernel.
>
> If we need explicit rcu_read_lock(), we should add rcu_read_lock()
> in cgroup_enable_task_cg_lists(), not cgroup_iter_*.
>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Seems reasonable. Thanks,
Paul
> ---
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 358e775..e6d92a5 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -2047,7 +2047,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
>
> ret = 0;
> cgrp = dentry->d_fsdata;
> - rcu_read_lock();
>
> cgroup_iter_start(cgrp, &it);
> while ((tsk = cgroup_iter_next(cgrp, &it))) {
> @@ -2072,7 +2071,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
> }
> cgroup_iter_end(cgrp, &it);
>
> - rcu_read_unlock();
> err:
> return ret;
> }
>
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2008-11-24 20:41 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2008-11-22 4:09 [PATCH] cgroups: remove rcu_read_lock() in cgroupstats_build() Lai Jiangshan
2008-11-24 20:41 ` Paul Menage
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.