Commit 9b3a7fd0 authored by Tony Luck's avatar Tony Luck Committed by Thomas Gleixner
Browse files

x86/intel_rdt: Add framework for better RDT UI diagnostics 



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 which
check that we hold the rdtgroup_mutex.

[ tglx: Made last_cmd_status static and folded back the hunk from patch 3
  	which replaces the open coded access to last_cmd_status with the
  	accessor function ]

Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vikas Shivappa <vikas.shivappa@intel.com>
Cc: Boris Petkov <bp@suse.de>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/edc4e0e9741eee89bba569f0021b1b2662fd9508.1506382469.git.tony.luck@intel.com
parent e19b205b

arch/x86/kernel/cpu/intel_rdt.h

+7 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

+56 −0
Original line number Diff line number Diff line
@@ -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;



static 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)

{
@@ -685,6 +726,13 @@ 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,
@@ -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 @@ out_info: 
out_cdp:

	cdp_disable();

out:

	rdt_last_cmd_clear();

	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;

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