Make cgroup_subtree_control_write() first calculate new
subtree_control (new_sc), child_subsys_mask (new_ss) and
css_enable/disable masks before applying them to the cgroup. Also,
store the original subtree_control (old_sc) and child_subsys_mask
(old_ss) and use them to restore the orignal state after failure.
This patch shouldn't cause any behavior changes. This prepares for a
fix for a bug in the async css offline wait logic.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
kernel/cgroup.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2653,7 +2653,7 @@ static ssize_t cgroup_subtree_control_wr
loff_t off)
{
unsigned int enable = 0, disable = 0;
- unsigned int css_enable, css_disable, old_ctrl, new_ctrl;
+ unsigned int css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
struct cgroup *cgrp, *child;
struct cgroup_subsys *ss;
char *tok;
@@ -2770,18 +2770,19 @@ static ssize_t cgroup_subtree_control_wr
* subsystems than specified may need to be enabled or disabled
* depending on subsystem dependencies.
*/
- cgrp->subtree_control |= enable;
- cgrp->subtree_control &= ~disable;
+ old_sc = cgrp->subtree_control;
+ old_ss = cgrp->child_subsys_mask;
+ new_sc = (old_sc | enable) & ~disable;
+ new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc);
- old_ctrl = cgrp->child_subsys_mask;
- cgroup_refresh_child_subsys_mask(cgrp);
- new_ctrl = cgrp->child_subsys_mask;
-
- css_enable = ~old_ctrl & new_ctrl;
- css_disable = old_ctrl & ~new_ctrl;
+ css_enable = ~old_ss & new_ss;
+ css_disable = old_ss & ~new_ss;
enable |= css_enable;
disable |= css_disable;
+ cgrp->subtree_control = new_sc;
+ cgrp->child_subsys_mask = new_ss;
+
/*
* Create new csses or make the existing ones visible. A css is
* created invisible if it's being implicitly enabled through
@@ -2844,9 +2845,8 @@ out_unlock:
return ret ?: nbytes;
err_undo_css:
- cgrp->subtree_control &= ~enable;
- cgrp->subtree_control |= disable;
- cgroup_refresh_child_subsys_mask(cgrp);
+ cgrp->subtree_control = old_sc;
+ cgrp->child_subsys_mask = old_ss;
for_each_subsys(ss, ssid) {
if (!(enable & (1 << ssid)))
--
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