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

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 3b62287a2f01dff99bd59ed086f28c5e3c94f07d..e61908169dcaf8e1b1aa226fda43b34df204ef7c 100644 (file)
--- 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;