[RFC PATCH mpam mpam/snapshot/v6.12-rc1 v2 6/6] fs/resctrl: Add the helper to check if the task exists in the target group

[Zeng Heng]

After introducing the extension for monitoring feature, to check if a
closid exists within the target control group, it is not only check if the
closid of the control group is the same, but also to recursively check if
there is a closid of sub-monitor groups is the same. Therefore, a new
helper task_belongs_to_ctrl_group() is added.

On the x86 side, the closid of the child monitor group is the same as its
parent control group's (only the rmid is different), hence
resctrl_arch_match_rmid() can directly use the closid of the child monitor
group. Meanwhile, task_belongs_to_ctrl_group() can replace
resctrl_arch_match_closid() to be compatible with the x86 arch.

Signed-off-by: Zeng Heng <zengheng4 at huawei.com>
---
 fs/resctrl/rdtgroup.c | 52 +++++++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 19 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 7ebf4bf75c94..7a188f3cceeb 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -589,19 +589,38 @@ static void update_task_closid_rmid(struct task_struct *t)
 
 static bool task_in_rdtgroup(struct task_struct *tsk, struct rdtgroup *rdtgrp)
 {
-	u32 closid, rmid = rdtgrp->mon.rmid;
+	u32 closid, rmid;
 
-	if (rdtgrp->type == RDTCTRL_GROUP)
-		closid = rdtgrp->closid;
-	else if (rdtgrp->type == RDTMON_GROUP)
-		closid = rdtgrp->mon.parent->closid;
-	else
-		return false;
+	closid = rdtgrp->closid;
+	rmid = rdtgrp->mon.rmid;
 
 	return resctrl_arch_match_closid(tsk, closid) &&
 	       resctrl_arch_match_rmid(tsk, closid, rmid);
 }
 
+/**
+ * task_belongs_to_ctrl_group - the helper to check if the task exists in
+ *				the target control group.
+ * @tsk: task to be checked
+ * @rdtgrp: target control group
+ */
+static bool task_belongs_to_ctrl_group(struct task_struct *tsk, struct rdtgroup *rdtgrp)
+{
+	struct rdtgroup *crdtgrp;
+
+	/* Check whether exists in contrl group self */
+	if (resctrl_arch_match_closid(tsk, rdtgrp->closid))
+		return true;
+
+	/* Check if exists in one of children monitor groups */
+	list_for_each_entry(crdtgrp, &rdtgrp->mon.crdtgrp_list, mon.crdtgrp_list) {
+		if (resctrl_arch_match_closid(tsk, crdtgrp->closid))
+			return true;
+	}
+
+	return false;
+}
+
 static int __rdtgroup_move_task(struct task_struct *tsk,
 				struct rdtgroup *rdtgrp)
 {
@@ -618,17 +637,13 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
 	 * their parent CTRL group.
 	 */
 	if (rdtgrp->type == RDTMON_GROUP &&
-	    !resctrl_arch_match_closid(tsk, rdtgrp->mon.parent->closid)) {
+	   !task_belongs_to_ctrl_group(tsk, rdtgrp->mon.parent)) {
 		rdt_last_cmd_puts("Can't move task to different control group\n");
 		return -EINVAL;
 	}
 
-	if (rdtgrp->type == RDTMON_GROUP)
-		resctrl_arch_set_closid_rmid(tsk, rdtgrp->mon.parent->closid,
-					     rdtgrp->mon.rmid);
-	else
-		resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid,
-					     rdtgrp->mon.rmid);
+	resctrl_arch_set_closid_rmid(tsk, rdtgrp->closid,
+				     rdtgrp->mon.rmid);
 
 	/*
 	 * Ensure the task's closid and rmid are written before determining if
@@ -652,14 +667,13 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
 static bool is_closid_match(struct task_struct *t, struct rdtgroup *r)
 {
 	return (resctrl_arch_alloc_capable() && (r->type == RDTCTRL_GROUP) &&
-		resctrl_arch_match_closid(t, r->closid));
+		task_belongs_to_ctrl_group(t, r));
 }
 
 static bool is_rmid_match(struct task_struct *t, struct rdtgroup *r)
 {
 	return (resctrl_arch_mon_capable() && (r->type == RDTMON_GROUP) &&
-		resctrl_arch_match_rmid(t, r->mon.parent->closid,
-					r->mon.rmid));
+		resctrl_arch_match_rmid(t, r->closid, r->mon.rmid));
 }
 
 /**
@@ -909,7 +923,7 @@ int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
 		    rdtg->mode != RDT_MODE_EXCLUSIVE)
 			continue;
 
-		if (!resctrl_arch_match_closid(tsk, rdtg->closid))
+		if (!task_belongs_to_ctrl_group(tsk, rdtg))
 			continue;
 
 		seq_printf(s, "res:%s%s\n", (rdtg == &rdtgroup_default) ? "/" : "",
@@ -917,7 +931,7 @@ int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
 		seq_puts(s, "mon:");
 		list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
 				    mon.crdtgrp_list) {
-			if (!resctrl_arch_match_rmid(tsk, crg->mon.parent->closid,
+			if (!resctrl_arch_match_rmid(tsk, crg->closid,
 						     crg->mon.rmid))
 				continue;
 			seq_printf(s, "%s", crg->kn->name);
-- 
2.25.1