[PATCH 5/5] x86/intel_rdt: Add diagnostics when making directories

["Luck, Tony" <tony.luck@intel.com>]

From: Tony Luck <tony.luck@intel.com>

Mostly this is about running out of RMIDs or CLOSIDs. Other
errors are various internal errors.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 8b851ae601df..dc8bc21cc6ee 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1574,8 +1574,10 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 	int ret;
 
 	prdtgrp = rdtgroup_kn_lock_live(prgrp_kn);
+	seq_buf_clear(&last_cmd_status);
 	if (!prdtgrp) {
 		ret = -ENODEV;
+		seq_buf_puts(&last_cmd_status, "directory was removed\n");
 		goto out_unlock;
 	}
 
@@ -1583,6 +1585,7 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 	rdtgrp = kzalloc(sizeof(*rdtgrp), GFP_KERNEL);
 	if (!rdtgrp) {
 		ret = -ENOSPC;
+		seq_buf_puts(&last_cmd_status, "kernel out of memory\n");
 		goto out_unlock;
 	}
 	*r = rdtgrp;
@@ -1594,6 +1597,7 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 	kn = kernfs_create_dir(parent_kn, name, mode, rdtgrp);
 	if (IS_ERR(kn)) {
 		ret = PTR_ERR(kn);
+		seq_buf_puts(&last_cmd_status, "kernfs create error\n");
 		goto out_free_rgrp;
 	}
 	rdtgrp->kn = kn;
@@ -1607,24 +1611,32 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 	kernfs_get(kn);
 
 	ret = rdtgroup_kn_set_ugid(kn);
-	if (ret)
+	if (ret) {
+		seq_buf_puts(&last_cmd_status, "kernfs perm error\n");
 		goto out_destroy;
+	}
 
 	files = RFTYPE_BASE | RFTYPE_CTRL;
 	files = RFTYPE_BASE | BIT(RF_CTRLSHIFT + rtype);
 	ret = rdtgroup_add_files(kn, files);
-	if (ret)
+	if (ret) {
+		seq_buf_puts(&last_cmd_status, "kernfs fill error\n");
 		goto out_destroy;
+	}
 
 	if (rdt_mon_capable) {
 		ret = alloc_rmid();
-		if (ret < 0)
+		if (ret < 0) {
+			seq_buf_puts(&last_cmd_status, "out of RMIDs\n");
 			goto out_destroy;
+		}
 		rdtgrp->mon.rmid = ret;
 
 		ret = mkdir_mondata_all(kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
-		if (ret)
+		if (ret) {
+			seq_buf_puts(&last_cmd_status, "kernfs subdir error\n");
 			goto out_idfree;
+		}
 	}
 	kernfs_activate(kn);
 
@@ -1702,8 +1714,10 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
 
 	kn = rdtgrp->kn;
 	ret = closid_alloc();
-	if (ret < 0)
+	if (ret < 0) {
+		seq_buf_puts(&last_cmd_status, "out of CLOSIDs\n");
 		goto out_common_fail;
+	}
 	closid = ret;
 
 	rdtgrp->closid = closid;
@@ -1715,8 +1729,10 @@ static int rdtgroup_mkdir_ctrl_mon(struct kernfs_node *parent_kn,
 		 * of tasks and cpus to monitor.
 		 */
 		ret = mongroup_create_dir(kn, NULL, "mon_groups", NULL);
-		if (ret)
+		if (ret) {
+			seq_buf_puts(&last_cmd_status, "kernfs subdir error\n");
 			goto out_id_free;
+		}
 	}
 
 	goto out_unlock;
-- 
2.11.0