Commit 307b675c authored by Tobias Huschle's avatar Tobias Huschle Committed by Vasily Gorbik
Browse files

s390/wti: Add debugfs file to display missed grace periods per cpu 



Introduce a new debug file which allows to determine how many warning
track grace periods were missed on each CPU.
The new file can be found as /sys/kernel/debug/s390/wti

It is formatted as:
       CPU0       CPU1   [...]    CPUx
        xyz        xyz   [...]     xyz

Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Reviewed-by: default avatarMete Durlu <meted@linux.ibm.com>
Signed-off-by: default avatarTobias Huschle <huschle@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 42419bcd

arch/s390/kernel/wti.c

+25 −0
Original line number Diff line number Diff line
@@ -5,6 +5,8 @@ 
 * Copyright IBM Corp. 2023

 */



#include <linux/cpu.h>

#include <linux/debugfs.h>

#include <linux/kallsyms.h>

#include <linux/smpboot.h>

#include <linux/irq.h>
@@ -117,6 +119,26 @@ static void wti_dbf_grace_period(struct wti_state *st) 
	wdi->missed++;

}



static int wti_show(struct seq_file *seq, void *v)

{

	struct wti_state *st;

	int cpu;



	cpus_read_lock();

	seq_puts(seq, "       ");

	for_each_online_cpu(cpu)

		seq_printf(seq, "CPU%-8d", cpu);

	seq_putc(seq, '\n');

	for_each_online_cpu(cpu) {

		st = per_cpu_ptr(&wti_state, cpu);

		seq_printf(seq, " %10lu", st->dbg.missed);

	}

	seq_putc(seq, '\n');

	cpus_read_unlock();

	return 0;

}

DEFINE_SHOW_ATTRIBUTE(wti);



static void wti_thread_fn(unsigned int cpu)

{

	struct wti_state *st = per_cpu_ptr(&wti_state, cpu);
@@ -143,6 +165,7 @@ static struct smp_hotplug_thread wti_threads = { 
static int __init wti_init(void)

{

	struct sched_param wti_sched_param = { .sched_priority = MAX_RT_PRIO - 1 };

	struct dentry *wti_dir;

	struct wti_state *st;

	int cpu, rc;
@@ -168,6 +191,8 @@ static int __init wti_init(void) 
		rc = -EOPNOTSUPP;

		goto out_subclass;

	}

	wti_dir = debugfs_create_dir("wti", arch_debugfs_dir);

	debugfs_create_file("stat", 0400, wti_dir, NULL, &wti_fops);

	wti_dbg = debug_register("wti", 1, 1, WTI_DBF_LEN);

	if (!wti_dbg) {

		rc = -ENOMEM;