[tip: x86/cache] fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy

[tip-bot2 for Reinette Chatre]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     b37678cfe51c21f291caa290d1f0e26c74c65060
Gitweb:        https://git.kernel.org/tip/b37678cfe51c21f291caa290d1f0e26c74c65060
Author:        Reinette Chatre <reinette.chatre@xxxxxxxxx>
AuthorDate:    Tue, 30 Jun 2026 21:27:08 -07:00
Committer:     Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Sun, 26 Jul 2026 21:22:37 -07:00

fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy

info/last_cmd_status is intended to contain more information if a write to
any resctrl file fails. Writes to max_threshold_occupancy did not receive
last_cmd_status support during initial last_cmd_status enabling. Add it now.

Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Link: https://patch.msgid.link/dfc60cf5324e15612db075b0987bd89c490fbad5.1782857711.git.reinette.chatre@xxxxxxxxx
---
 fs/resctrl/rdtgroup.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 3020f44..72347d1 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1299,14 +1299,20 @@ static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
 	unsigned int bytes;
 	int ret;
 
-	ret = kstrtouint(buf, 0, &bytes);
-	if (ret)
-		return ret;
-
 	if (!info_kn_lock(of->kn))
 		return -ENOENT;
 
+	rdt_last_cmd_clear();
+
+	ret = kstrtouint(buf, 0, &bytes);
+	if (ret) {
+		rdt_last_cmd_puts("max_threshold_occupancy: Invalid input\n");
+		goto out_unlock;
+	}
+
 	if (bytes > resctrl_rmid_realloc_limit) {
+		rdt_last_cmd_printf("max_threshold_occupancy: Exceeds limit (before adjustment) of %u bytes\n",
+				    resctrl_rmid_realloc_limit);
 		ret = -EINVAL;
 		goto out_unlock;
 	}