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Subject[PATCH 21/28] x86/intel_rdt/cqm: Add rmdir support
Date
Resource groups (ctrl_mon and monitor groups) are represented by
directories in resctrl fs. Add support to remove the directories.

When a ctrl_mon directory is removed all the cpus and tasks are assigned
back to the root rdtgroup. When a monitor group is removed the cpus and
tasks are returned to the parent control group.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 90 ++++++++++++++++++++++++++++++--
1 file changed, 86 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 59251592..a5e6d60 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1131,6 +1131,18 @@ static int reset_all_ctrls(struct rdt_resource *r)
return 0;
}

+static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
+{
+ return (rdt_alloc_capable &&
+ (r->type == RDTCTRL_GROUP) && (t->closid == r->closid));
+}
+
+static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
+{
+ return (rdt_mon_capable &&
+ (r->type == RDTMON_GROUP) && (t->rmid == r->mon.rmid));
+}
+
/*
* Move tasks from one to the other group. If @from is NULL, then all tasks
* in the systems are moved unconditionally (used for teardown).
@@ -1146,8 +1158,11 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,

read_lock(&tasklist_lock);
for_each_process_thread(p, t) {
- if (!from || t->closid == from->closid) {
+ if (!from || is_closid_match(t, from) ||
+ is_rmid_match(t, from)) {
t->closid = to->closid;
+ t->rmid = to->mon.rmid;
+
#ifdef CONFIG_SMP
/*
* This is safe on x86 w/o barriers as the ordering
@@ -1166,6 +1181,19 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
read_unlock(&tasklist_lock);
}

+static void free_all_child_rdtgrp(struct rdtgroup *rdtgrp)
+{
+ struct rdtgroup *sentry, *stmp;
+ struct list_head *head;
+
+ head = &rdtgrp->mon.crdtgrp_list;
+ list_for_each_entry_safe(sentry, stmp, head, mon.crdtgrp_list) {
+ free_rmid(sentry->mon.rmid);
+ list_del(&sentry->mon.crdtgrp_list);
+ kfree(sentry);
+ }
+}
+
/*
* Forcibly remove all of subdirectories under root.
*/
@@ -1568,6 +1596,44 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
return -EPERM;
}

+static int rdtgroup_rmdir_mon(struct kernfs_node *kn, struct rdtgroup *rdtgrp,
+ cpumask_var_t tmpmask)
+{
+ struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
+ int cpu;
+
+ /* Give any tasks back to the parent group */
+ rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
+
+ /* Update per cpu rmid of the moved CPUs first */
+ for_each_cpu(cpu, &rdtgrp->cpu_mask)
+ per_cpu(rdt_cpu_default.rmid, cpu) = prdtgrp->mon.rmid;
+ /*
+ * Update the MSR on moved CPUs and CPUs which have moved
+ * task running on them.
+ */
+ cpumask_or(tmpmask, tmpmask, &rdtgrp->cpu_mask);
+ update_closid_rmid(tmpmask, NULL);
+
+ rdtgrp->flags = RDT_DELETED;
+ free_rmid(rdtgrp->mon.rmid);
+
+ /*
+ * Remove the rdtgrp from the parent ctrl_mon group's list
+ */
+ WARN_ON(list_empty(&prdtgrp->mon.crdtgrp_list));
+ list_del(&rdtgrp->mon.crdtgrp_list);
+
+ /*
+ * one extra hold on this, will drop when we kfree(rdtgrp)
+ * in rdtgroup_kn_unlock()
+ */
+ kernfs_get(kn);
+ kernfs_remove(rdtgrp->kn);
+
+ return 0;
+}
+
static int rdtgroup_rmdir_ctrl(struct kernfs_node *kn, struct rdtgroup *rdtgrp,
cpumask_var_t tmpmask)
{
@@ -1580,9 +1646,12 @@ static int rdtgroup_rmdir_ctrl(struct kernfs_node *kn, struct rdtgroup *rdtgrp,
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);

- /* Update per cpu closid of the moved CPUs first */
- for_each_cpu(cpu, &rdtgrp->cpu_mask)
+ /* Update per cpu closid and rmid of the moved CPUs first */
+ for_each_cpu(cpu, &rdtgrp->cpu_mask) {
per_cpu(rdt_cpu_default.closid, cpu) = rdtgroup_default.closid;
+ per_cpu(rdt_cpu_default.rmid, cpu) = rdtgroup_default.mon.rmid;
+ }
+
/*
* Update the MSR on moved CPUs and CPUs which have moved
* task running on them.
@@ -1592,6 +1661,13 @@ static int rdtgroup_rmdir_ctrl(struct kernfs_node *kn, struct rdtgroup *rdtgrp,

rdtgrp->flags = RDT_DELETED;
closid_free(rdtgrp->closid);
+ free_rmid(rdtgrp->mon.rmid);
+
+ /*
+ * Free all the child monitor group rmids.
+ */
+ free_all_child_rdtgrp(rdtgrp);
+
list_del(&rdtgrp->rdtgroup_list);

/*
@@ -1622,10 +1698,16 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)

/*
* If the rdtgroup is a ctrl_mon group and parent directory
- * is the root directory, remove the ctrl group.
+ * is the root directory, remove the ctrl_mon group.
+ *
+ * If the rdtgroup is a mon group and parent directory
+ * is a valid "mon_groups" directory, remove the mon group.
*/
if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn)
ret = rdtgroup_rmdir_ctrl(kn, rdtgrp, tmpmask);
+ else if (rdtgrp->type == RDTMON_GROUP &&
+ is_mon_groups(parent_kn, kn->name))
+ ret = rdtgroup_rmdir_mon(kn, rdtgrp, tmpmask);
else
ret = -EPERM;

--
1.9.1
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