From 854db793d4073087fa799d886ed84a342e3f484a Mon Sep 17 00:00:00 2001 From: Reinette Chatre Date: Tue, 30 Jun 2026 21:27:10 -0700 Subject: [PATCH] fs/resctrl: Inform user space when status buffer overflowed resctrl fs commands are becoming more powerful with, for example, a user able to use syntax like '*' to make broad configuration changes. Such commands that span multiple domains may result in more than one message printed to the last_cmd_status buffer with more planned. Issue "[truncated]" when displaying the last_cmd_status buffer to communicate if it overflowed. Upon encountering this, user space is expected to combine details about the failure found in info/last_cmd_status with related resctrl files to learn the accurate system state after the command failure. Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Ben Horgan Reviewed-by: Tony Luck Tested-by: Babu Moger Link: https://patch.msgid.link/eb3d1aaa41d1f2bf6b1bb26ceafd52f04912121d.1782857711.git.reinette.chatre@intel.com --- fs/resctrl/rdtgroup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 08d58c4e9acb..5dcbb0a964e8 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -979,10 +979,13 @@ static int rdt_last_cmd_status_show(struct kernfs_open_file *of, if (!info_kn_lock(of->kn)) return -ENOENT; len = seq_buf_used(&last_cmd_status); - if (len) + if (len) { seq_printf(seq, "%.*s", len, last_cmd_status_buf); - else + if (seq_buf_has_overflowed(&last_cmd_status)) + seq_puts(seq, "[truncated]\n"); + } else { seq_puts(seq, "ok\n"); + } info_kn_unlock(of->kn); return 0; }