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Date: Mon, 25 Sep 2017 16:39:33 -0700
From: "Luck, Tony" <tony.luck@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
Boris Petkov <bp@...e.de>, Fenghua Yu <fenghua.yu@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Steven Rostedt <rostedt@...dmis.org>,
Vikas Shivappa <vikas.shivappa@...el.com>
Subject: [PATCH v2 1/6] x86/intel_rdt: Add framework for better RDT UI diagnostics
From: Tony Luck <tony.luck@...el.com>
Commands are given to the resctrl file system by making/removing
directories, or by writing to files. When something goes wrong
the user is generally left wondering why they got:
bash: echo: write error: Invalid argument
Add a new file "last_cmd_status" to the "info" directory that
will give the user some better clues on what went wrong.
Provide functions to clear and update last_cmd_status
that check that we hold the rdtgroup_mutex.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
arch/x86/kernel/cpu/intel_rdt.h | 7 ++++
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 56 ++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+)
diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index ebaddaeef023..9d3148d88ec8 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -126,12 +126,15 @@ struct rdtgroup {
#define RFTYPE_BASE BIT(1)
#define RF_CTRLSHIFT 4
#define RF_MONSHIFT 5
+#define RF_TOPSHIFT 6
#define RFTYPE_CTRL BIT(RF_CTRLSHIFT)
#define RFTYPE_MON BIT(RF_MONSHIFT)
+#define RFTYPE_TOP BIT(RF_TOPSHIFT)
#define RFTYPE_RES_CACHE BIT(8)
#define RFTYPE_RES_MB BIT(9)
#define RF_CTRL_INFO (RFTYPE_INFO | RFTYPE_CTRL)
#define RF_MON_INFO (RFTYPE_INFO | RFTYPE_MON)
+#define RF_TOP_INFO (RFTYPE_INFO | RFTYPE_TOP)
#define RF_CTRL_BASE (RFTYPE_BASE | RFTYPE_CTRL)
/* List of all resource groups */
@@ -408,6 +411,10 @@ union cpuid_0x10_x_edx {
unsigned int full;
};
+void rdt_last_cmd_clear(void);
+void rdt_last_cmd_puts(const char *s);
+void rdt_last_cmd_printf(const char *fmt, ...);
+
void rdt_ctrl_update(void *arg);
struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn);
void rdtgroup_kn_unlock(struct kernfs_node *kn);
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index a869d4a073c5..9268122eb149 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -24,6 +24,7 @@
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/kernfs.h>
+#include <linux/seq_buf.h>
#include <linux/seq_file.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
@@ -51,6 +52,31 @@ static struct kernfs_node *kn_mongrp;
/* Kernel fs node for "mon_data" directory under root */
static struct kernfs_node *kn_mondata;
+struct seq_buf last_cmd_status;
+static char last_cmd_status_buf[512];
+
+void rdt_last_cmd_clear(void)
+{
+ lockdep_assert_held(&rdtgroup_mutex);
+ seq_buf_clear(&last_cmd_status);
+}
+
+void rdt_last_cmd_puts(const char *s)
+{
+ lockdep_assert_held(&rdtgroup_mutex);
+ seq_buf_puts(&last_cmd_status, s);
+}
+
+void rdt_last_cmd_printf(const char *fmt, ...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ lockdep_assert_held(&rdtgroup_mutex);
+ seq_buf_vprintf(&last_cmd_status, fmt, ap);
+ va_end(ap);
+}
+
/*
* Trivial allocator for CLOSIDs. Since h/w only supports a small number,
* we can keep a bitmap of free CLOSIDs in a single integer.
@@ -569,6 +595,21 @@ static int rdtgroup_tasks_show(struct kernfs_open_file *of,
return ret;
}
+static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
+ struct seq_file *seq, void *v)
+{
+ int len;
+
+ mutex_lock(&rdtgroup_mutex);
+ len = seq_buf_used(&last_cmd_status);
+ if (len)
+ seq_printf(seq, "%.*s", len, last_cmd_status_buf);
+ else
+ seq_puts(seq, "ok\n");
+ mutex_unlock(&rdtgroup_mutex);
+ return 0;
+}
+
static int rdt_num_closids_show(struct kernfs_open_file *of,
struct seq_file *seq, void *v)
{
@@ -686,6 +727,13 @@ static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
{
+ .name = "last_cmd_status",
+ .mode = 0444,
+ .kf_ops = &rdtgroup_kf_single_ops,
+ .seq_show = rdt_last_cmd_status_show,
+ .fflags = RF_TOP_INFO,
+ },
+ {
.name = "num_closids",
.mode = 0444,
.kf_ops = &rdtgroup_kf_single_ops,
@@ -855,6 +903,10 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
return PTR_ERR(kn_info);
kernfs_get(kn_info);
+ ret = rdtgroup_add_files(kn_info, RF_TOP_INFO);
+ if (ret)
+ goto out_destroy;
+
for_each_alloc_enabled_rdt_resource(r) {
fflags = r->fflags | RF_CTRL_INFO;
ret = rdtgroup_mkdir_info_resdir(r, r->name, fflags);
@@ -1156,6 +1208,7 @@ static struct dentry *rdt_mount(struct file_system_type *fs_type,
out_cdp:
cdp_disable();
out:
+ seq_buf_clear(&last_cmd_status);
mutex_unlock(&rdtgroup_mutex);
return dentry;
@@ -1902,6 +1955,9 @@ int __init rdtgroup_init(void)
{
int ret = 0;
+ seq_buf_init(&last_cmd_status, last_cmd_status_buf,
+ sizeof(last_cmd_status_buf));
+
ret = rdtgroup_setup_root();
if (ret)
return ret;
--
2.11.0
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