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authorTejun Heo <tj@kernel.org>2014-07-08 18:02:56 -0400
committerTejun Heo <tj@kernel.org>2014-07-08 18:02:56 -0400
commitc29adf24e0c443fb4433efb6a62bd91fdb739c34 (patch)
tree99a57e738ef088cbadbb6073601361a8d46ebc82 /kernel/cgroup.c
parenta497c3ba1d97fc69c1e78e7b96435ba8c2cb42ee (diff)
downloadlwn-c29adf24e0c443fb4433efb6a62bd91fdb739c34.tar.gz
lwn-c29adf24e0c443fb4433efb6a62bd91fdb739c34.zip
cgroup: reorganize cgroup_subtree_control_write()
Make the following two reorganizations to cgroup_subtree_control_write(). These are to prepare for future changes and shouldn't cause any functional difference. * Move availability above css offlining wait. * Move cgrp->child_subsys_mask update above new css creation. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c34
1 files changed, 17 insertions, 17 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 7868fc3c0bc5..a46d7e2012b4 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2613,6 +2613,14 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
continue;
}
+ /* unavailable or not enabled on the parent? */
+ if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
+ (cgroup_parent(cgrp) &&
+ !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {
+ ret = -ENOENT;
+ goto out_unlock;
+ }
+
/*
* Because css offlining is asynchronous, userland
* might try to re-enable the same controller while
@@ -2635,14 +2643,6 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
return restart_syscall();
}
-
- /* unavailable or not enabled on the parent? */
- if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
- (cgroup_parent(cgrp) &&
- !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ssid)))) {
- ret = -ENOENT;
- goto out_unlock;
- }
} else if (disable & (1 << ssid)) {
if (!(cgrp->child_subsys_mask & (1 << ssid))) {
disable &= ~(1 << ssid);
@@ -2673,12 +2673,10 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
goto out_unlock;
}
- /*
- * Create csses for enables and update child_subsys_mask. This
- * changes cgroup_e_css() results which in turn makes the
- * subsequent cgroup_update_dfl_csses() associate all tasks in the
- * subtree to the updated csses.
- */
+ cgrp->child_subsys_mask |= enable;
+ cgrp->child_subsys_mask &= ~disable;
+
+ /* create new csses */
for_each_subsys(ss, ssid) {
if (!(enable & (1 << ssid)))
continue;
@@ -2690,9 +2688,11 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
}
}
- cgrp->child_subsys_mask |= enable;
- cgrp->child_subsys_mask &= ~disable;
-
+ /*
+ * At this point, cgroup_e_css() results reflect the new csses
+ * making the following cgroup_update_dfl_csses() properly update
+ * css associations of all tasks in the subtree.
+ */
ret = cgroup_update_dfl_csses(cgrp);
if (ret)
goto err_undo_css;