linux-kernel - [PATCH v10 22/28] fs/resctrl: Move allocation/free of closid_num_dirty

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Message-ID: <20250912221053.11349-23-tony.luck@intel.com>
Date: Fri, 12 Sep 2025 15:10:43 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v10 22/28] fs/resctrl: Move allocation/free of closid_num_dirty_rmid[]

closid_num_dirty_rmid[] is allocated in dom_data_init() during resctrl
initialization and freed by dom_data_exit() during resctrl exit giving
it the same life cycle as rmid_ptrs[].

Move closid_num_dirty_rmid[] allocaction/free out to
resctrl_l3_mon_resource_init() and resctrl_l3_mon_resource_exit() in
preparation for rmid_ptrs[] to be allocated on resctrl mount in support
of the new telemetry events.

Keep the rdtgroup_mutex protection around the allocation/free of
closid_num_dirty_rmid[] as ARM needs this to guarantee memory
ordering.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 fs/resctrl/monitor.c | 77 ++++++++++++++++++++++++++++----------------
 1 file changed, 49 insertions(+), 28 deletions(-)

diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 6b22d2815734..8f15bdf40593 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -885,36 +885,14 @@ void mbm_setup_overflow_handler(struct rdt_l3_mon_domain *dom, unsigned long del
 static int dom_data_init(struct rdt_resource *r)
 {
 	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
-	u32 num_closid = resctrl_arch_get_num_closid(r);
 	struct rmid_entry *entry = NULL;
 	int err = 0, i;
 	u32 idx;
 
 	mutex_lock(&rdtgroup_mutex);
-	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
-		u32 *tmp;
-
-		/*
-		 * If the architecture hasn't provided a sanitised value here,
-		 * this may result in larger arrays than necessary. Resctrl will
-		 * use a smaller system wide value based on the resources in
-		 * use.
-		 */
-		tmp = kcalloc(num_closid, sizeof(*tmp), GFP_KERNEL);
-		if (!tmp) {
-			err = -ENOMEM;
-			goto out_unlock;
-		}
-
-		closid_num_dirty_rmid = tmp;
-	}
 
 	rmid_ptrs = kcalloc(idx_limit, sizeof(struct rmid_entry), GFP_KERNEL);
 	if (!rmid_ptrs) {
-		if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
-			kfree(closid_num_dirty_rmid);
-			closid_num_dirty_rmid = NULL;
-		}
 		err = -ENOMEM;
 		goto out_unlock;
 	}
@@ -950,11 +928,6 @@ static void dom_data_exit(struct rdt_resource *r)
 	if (!r->mon_capable)
 		goto out_unlock;
 
-	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
-		kfree(closid_num_dirty_rmid);
-		closid_num_dirty_rmid = NULL;
-	}
-
 	kfree(rmid_ptrs);
 	rmid_ptrs = NULL;
 
@@ -1791,6 +1764,43 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
 	return ret ?: nbytes;
 }
 
+static int closid_num_dirty_rmid_alloc(struct rdt_resource *r)
+{
+	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
+		u32 num_closid = resctrl_arch_get_num_closid(r);
+		u32 *tmp;
+
+		/* For ARM memory ordering access to closid_num_dirty_rmid */
+		mutex_lock(&rdtgroup_mutex);
+
+		/*
+		 * If the architecture hasn't provided a sanitised value here,
+		 * this may result in larger arrays than necessary. Resctrl will
+		 * use a smaller system wide value based on the resources in
+		 * use.
+		 */
+		tmp = kcalloc(num_closid, sizeof(*tmp), GFP_KERNEL);
+		if (!tmp)
+			return -ENOMEM;
+
+		closid_num_dirty_rmid = tmp;
+
+		mutex_unlock(&rdtgroup_mutex);
+	}
+
+	return 0;
+}
+
+static void closid_num_dirty_rmid_free(void)
+{
+	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
+		mutex_lock(&rdtgroup_mutex);
+		kfree(closid_num_dirty_rmid);
+		closid_num_dirty_rmid = NULL;
+		mutex_unlock(&rdtgroup_mutex);
+	}
+}
+
 /**
  * resctrl_l3_mon_resource_init() - Initialise global monitoring structures.
  *
@@ -1811,10 +1821,16 @@ int resctrl_l3_mon_resource_init(void)
 	if (!r->mon_capable)
 		return 0;
 
-	ret = dom_data_init(r);
+	ret = closid_num_dirty_rmid_alloc(r);
 	if (ret)
 		return ret;
 
+	ret = dom_data_init(r);
+	if (ret) {
+		closid_num_dirty_rmid_free();
+		return ret;
+	}
+
 	if (resctrl_arch_is_evt_configurable(QOS_L3_MBM_TOTAL_EVENT_ID)) {
 		mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].configurable = true;
 		resctrl_file_fflags_init("mbm_total_bytes_config",
@@ -1859,5 +1875,10 @@ void resctrl_l3_mon_resource_exit(void)
 {
 	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
 
+	if (!r->mon_capable)
+		return;
+
+	closid_num_dirty_rmid_free();
+
 	dom_data_exit(r);
 }
-- 
2.51.0