[PATCH 15/21] x86/intel_rdt/cqm: Add rmdir support

[Vikas Shivappa]

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@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 110 +++++++++++++++++++++++++++----
 1 file changed, 99 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 9377bcd..6131508 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1164,6 +1164,18 @@ 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_enabled &&
+		(r->type == RDTCTRL_GROUP) && (t->closid == r->closid));
+}
+
+static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
+{
+	return (rdt_mon_features &&
+		(r->type == RDTMON_GROUP) && (t->rmid == r->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).
@@ -1179,8 +1191,11 @@ 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->rmid;
+
 #ifdef CONFIG_SMP
 			/*
 			 * This is safe on x86 w/o barriers as the ordering
@@ -1402,6 +1417,7 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn, struct rdtgroup *pr,
 	kernfs_remove(kn);
 	return ret;
 }
+
 /*
  * Common code for ctrl_mon and monitor group mkdir.
  * The caller needs to unlock the global mutex upon success.
@@ -1588,20 +1604,57 @@ static int rdtgroup_mkdir(struct kernfs_node *pkn, const char *name,
 		return -EPERM;
 }
 
-static int rdtgroup_rmdir(struct kernfs_node *kn)
+static int rdtgroup_rmdir_mon(struct kernfs_node *kn, struct rdtgroup *rdtgrp)
 {
-	int ret, cpu, closid = rdtgroup_default.closid;
-	struct rdtgroup *rdtgrp;
+	struct rdtgroup *prdtgrp = rdtgrp->parent;
 	cpumask_var_t tmpmask;
+	int cpu;
 
 	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
 		return -ENOMEM;
 
-	rdtgrp = rdtgroup_kn_lock_live(kn);
-	if (!rdtgrp) {
-		ret = -EPERM;
-		goto out;
-	}
+	/* 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(cpu_rmid, cpu) = prdtgrp->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->rmid);
+
+	/*
+	 * Remove your rmid from the parent ctrl groups list
+	 */
+	WARN_ON(list_empty(&prdtgrp->crdtgrp_list));
+	list_del(&rdtgrp->crdtgrp_list);
+
+	/*
+	 * one extra hold on this, will drop when we kfree(rdtgrp)
+	 * in rdtgroup_kn_unlock()
+	 */
+	kernfs_get(kn);
+	kernfs_remove(rdtgrp->kn);
+	free_cpumask_var(tmpmask);
+
+	return 0;
+}
+
+static int rdtgroup_rmdir_ctrl(struct kernfs_node *kn, struct rdtgroup *rdtgrp)
+{
+	int cpu, closid = rdtgroup_default.closid;
+	struct rdtgroup *entry, *tmp;
+	struct list_head *llist;
+	cpumask_var_t tmpmask;
+
+	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+		return -ENOMEM;
 
 	/* Give any tasks back to the default group */
 	rdt_move_group_tasks(rdtgrp, &rdtgroup_default, tmpmask);
@@ -1622,6 +1675,18 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
 
 	rdtgrp->flags = RDT_DELETED;
 	closid_free(rdtgrp->closid);
+	free_rmid(rdtgrp->rmid);
+
+	/*
+	 * Free all the child monitor group rmids.
+	 */
+	llist = &rdtgrp->crdtgrp_list;
+	list_for_each_entry_safe(entry, tmp, llist, crdtgrp_list) {
+		free_rmid(entry->rmid);
+		list_del(&entry->crdtgrp_list);
+		kfree(entry);
+	}
+
 	list_del(&rdtgrp->rdtgroup_list);
 
 	/*
@@ -1630,10 +1695,33 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
 	 */
 	kernfs_get(kn);
 	kernfs_remove(rdtgrp->kn);
-	ret = 0;
+	free_cpumask_var(tmpmask);
+
+	return 0;
+}
+
+static int rdtgroup_rmdir(struct kernfs_node *kn)
+{
+	struct kernfs_node *parent_kn = kn->parent;
+	struct rdtgroup *rdtgrp;
+	int ret = 0;
+
+	rdtgrp = rdtgroup_kn_lock_live(kn);
+	if (!rdtgrp) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	if (rdtgrp->type == RDTCTRL_GROUP && parent_kn == rdtgroup_default.kn)
+		ret = rdtgroup_rmdir_ctrl(kn, rdtgrp);
+	else if (rdtgrp->type == RDTMON_GROUP &&
+		 !strcmp(parent_kn->name, "mon_groups"))
+		ret = rdtgroup_rmdir_mon(kn, rdtgrp);
+	else
+		ret = -EPERM;
+
 out:
 	rdtgroup_kn_unlock(kn);
-	free_cpumask_var(tmpmask);
 	return ret;
 }
 
-- 
1.9.1