From c29adf24e0c443fb4433efb6a62bd91fdb739c34 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 8 Jul 2014 18:02:56 -0400 Subject: [PATCH] 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 Acked-by: Li Zefan Acked-by: Johannes Weiner --- kernel/cgroup.c | 34 +++++++++++++++++----------------- 1 file 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;