x86/intel_rdt/cqm: Add rmdir support

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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-22-git-send-email-vikas.shivappa@linux.intel.com

1 files 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 3b62287a2f01..e61908169dca 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1130,6 +1130,18 @@ 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).
@@ -1145,8 +1157,11 @@ 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
@@ -1165,6 +1180,19 @@ 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.
  */
@@ -1565,6 +1593,44 @@ 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)
 {
@@ -1577,9 +1643,12 @@ 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.
@@ -1589,6 +1658,13 @@ 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);
 
         /*
@@ -1619,10 +1695,16 @@ 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;