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.
This patch also drops cgroup_refresh_subtree_ss_mask(). It's a thin
wrapper which saves a bit of typing but the saving is pretty small and
planned changes will make its uses look inconsistent compared to
usages which don't update cgroups.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
kernel/cgroup.c | 42 ++++++++++++++++--------------------------
1 file changed, 16 insertions(+), 26 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a1f82fa..15461c7 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1301,18 +1301,17 @@ 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;
@@ -1320,9 +1319,6 @@ 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;
@@ -1335,7 +1331,7 @@ 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;
@@ -1346,19 +1342,6 @@ static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)
}
/**
- * cgroup_refresh_subtree_ss_mask - update subtree_ss_mask
- * @cgrp: the target cgroup
- *
- * Update @cgrp->subtree_ss_mask according to the current
- * @cgrp->subtree_control using cgroup_calc_subtree_ss_mask().
- */
-static void cgroup_refresh_subtree_ss_mask(struct cgroup *cgrp)
-{
- cgrp->subtree_ss_mask =
- cgroup_calc_subtree_ss_mask(cgrp, cgrp->subtree_control);
-}
-
-/**
* cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
* @kn: the kernfs_node being serviced
*
@@ -1592,7 +1575,9 @@ static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
src_root->subsys_mask &= ~(1 << ssid);
scgrp->subtree_control &= ~(1 << ssid);
- cgroup_refresh_subtree_ss_mask(scgrp);
+ scgrp->subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(scgrp->subtree_control,
+ cgroup_ss_mask(scgrp));
/* default hierarchy doesn't enable controllers by default */
dst_root->subsys_mask |= 1 << ssid;
@@ -1600,7 +1585,9 @@ static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
} else {
dcgrp->subtree_control |= 1 << ssid;
- cgroup_refresh_subtree_ss_mask(dcgrp);
+ dcgrp->subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(dcgrp->subtree_control,
+ cgroup_ss_mask(dcgrp));
static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
}
@@ -3059,8 +3046,9 @@ 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));
}
}
@@ -5108,7 +5096,9 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
*/
if (!cgroup_on_dfl(cgrp)) {
cgrp->subtree_control = cgroup_control(cgrp);
- cgroup_refresh_subtree_ss_mask(cgrp);
+ cgrp->subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(cgrp->subtree_control,
+ cgroup_ss_mask(cgrp));
}
return cgrp;
--
2.5.0
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