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cgroup: make cgroup_calc_subtree_ss_mask() take @this_ss_mask

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cgroup_calc_subtree_ss_mask() currently takes @cgrp and
@subtree_control.  @cgrp is used for two purposes - to decide whether
it's for default hierarchy and the mask of available subsystems.  The
former doesn't matter as the results are the same regardless.  The
latter can be specified directly through a subsystem mask.

This patch makes cgroup_calc_subtree_ss_mask() perform the same
calculations for both default and legacy hierarchies and take
@this_ss_mask for available subsystems.  @cgrp is no longer used and
dropped.  This is to allow using the function in contexts where
available controllers can't be decided from the cgroup.

v2: cgroup_refres_subtree_ss_mask() is removed by a previous patch.
    Updated accordingly.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2016-03-03 09:58:01 -05:00
parent 334c3679ec
commit 5ced2518bd
1 changed files with 7 additions and 10 deletions
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17
kernel/cgroup.c
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@ -1309,18 +1309,17 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
/**
* cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
* @cgrp: the target cgroup
* @subtree_control: the new subtree_control mask to consider
* @this_ss_mask: available subsystems
*
* On the default hierarchy, a subsystem may request other subsystems to be
* enabled together through its ->depends_on mask. In such cases, more
* subsystems than specified in "cgroup.subtree_control" may be enabled.
*
* This function calculates which subsystems need to be enabled if
* @subtree_control is to be applied to @cgrp. The returned mask is always
* a superset of @subtree_control and follows the usual hierarchy rules.
* @subtree_control is to be applied while restricted to @this_ss_mask.
*/
static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)
static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
{
u16 cur_ss_mask = subtree_control;
struct cgroup_subsys *ss;
@ -1328,9 +1327,6 @@ static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)
lockdep_assert_held(&cgroup_mutex);
if (!cgroup_on_dfl(cgrp))
return cur_ss_mask;
while (true) {
u16 new_ss_mask = cur_ss_mask;
@ -1343,7 +1339,7 @@ static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)
* happen only if some depended-upon subsystems were bound
* to non-default hierarchies.
*/
new_ss_mask &= cgroup_ss_mask(cgrp);
new_ss_mask &= this_ss_mask;
if (new_ss_mask == cur_ss_mask)
break;
@ -3012,8 +3008,9 @@ static void cgroup_propagate_control(struct cgroup *cgrp)
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
dsct->subtree_control &= cgroup_control(dsct);
dsct->subtree_ss_mask = cgroup_calc_subtree_ss_mask(dsct,
dsct->subtree_control);
dsct->subtree_ss_mask =
cgroup_calc_subtree_ss_mask(dsct->subtree_control,
cgroup_ss_mask(dsct));
}
}