linux-kernel - [RFC PATCH 3/7] x86/resctrl: Add driver callback when directories are removed

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Date:   Thu, 20 Apr 2023 15:06:32 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        James Morse <james.morse@....com>,
        Babu Moger <babu.moger@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Tony Luck <tony.luck@...el.com>
Subject: [RFC PATCH 3/7] x86/resctrl: Add driver callback when directories are removed

When a resctrl directory is removed, entities attached to that
directory are reassigned with the CLOSID and RMID of the parent
directory.

Add a callback function so a driver can reset the CLOSID and RMID
of any resources attached to the removed directory.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 include/linux/resctrl.h                |  2 ++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 7847be48edae..44dd811cb552 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -216,12 +216,14 @@ struct resctrl_fileinfo {
  * @mount:	Callback for mount/unmount
  * @infodir:	Name of directory to create in resctrl/info.
  * @infofiles:	Array of files to create under infodir.
+ * @rmdir:	Callback when a resctrl directory is removed.
  */
 struct resctrl_driver {
 	struct list_head	list;
 	void			(*mount)(bool mount);
 	char			*infodir;
 	struct resctrl_fileinfo	*infofiles;
+	int			(*rmdir)(int oclos, int ormid, int nclos, int nrmid);
 };
 
 int resctrl_register_driver(struct resctrl_driver *d);
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 4c662e827097..8ca3b17bd671 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3495,11 +3495,18 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
 static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 {
 	struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
+	struct resctrl_driver *d;
 	int cpu;
 
 	/* Give any tasks back to the parent group */
 	rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
 
+	list_for_each_entry(d, &drivers, list) {
+		if (d->rmdir)
+			d->rmdir(rdtgrp->closid, rdtgrp->mon.rmid,
+				 prdtgrp->closid, prdtgrp->mon.rmid);
+	}
+
 	/* Update per cpu rmid of the moved CPUs first */
 	for_each_cpu(cpu, &rdtgrp->cpu_mask)
 		per_cpu(pqr_state.default_rmid, cpu) = prdtgrp->mon.rmid;
@@ -3535,6 +3542,7 @@ static int rdtgroup_ctrl_remove(struct rdtgroup *rdtgrp)
 
 static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 {
+	struct resctrl_driver *d;
 	int cpu;
 
 	/* Give any tasks back to the default group */
@@ -3544,6 +3552,11 @@ static int rdtgroup_rmdir_ctrl(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
 	cpumask_or(&rdtgroup_default.cpu_mask,
 		   &rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
 
+	list_for_each_entry(d, &drivers, list) {
+		if (d->rmdir)
+			d->rmdir(rdtgrp->closid, rdtgrp->mon.rmid, 0, 0);
+	}
+
 	/* Update per cpu closid and rmid of the moved CPUs first */
 	for_each_cpu(cpu, &rdtgrp->cpu_mask) {
 		per_cpu(pqr_state.default_closid, cpu) = rdtgroup_default.closid;
-- 
2.39.2