From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file

---
 kernel/kernel/latencytop.c |   61 +++++++++---------------------
 1 files changed, 19 insertions(+), 42 deletions(-)

diff --git a/kernel/kernel/latencytop.c b/kernel/kernel/latencytop.c
index 96b4179..166d7bf 100644
--- a/kernel/kernel/latencytop.c
+++ b/kernel/kernel/latencytop.c
@@ -1,13 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * latencytop.c: Latency display infrastructure
  *
  * (C) Copyright 2008 Intel Corporation
  * Author: Arjan van de Ven <arjan@linux.intel.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; version 2
- * of the License.
  */
 
 /*
@@ -67,12 +63,9 @@
 
 int latencytop_enabled;
 
-void clear_all_latency_tracing(struct task_struct *p)
+void clear_tsk_latency_tracing(struct task_struct *p)
 {
 	unsigned long flags;
-
-	if (!latencytop_enabled)
-		return;
 
 	raw_spin_lock_irqsave(&latency_lock, flags);
 	memset(&p->latency_record, 0, sizeof(p->latency_record));
@@ -96,9 +89,6 @@
 	int firstnonnull = MAXLR + 1;
 	int i;
 
-	if (!latencytop_enabled)
-		return;
-
 	/* skip kernel threads for now */
 	if (!tsk->mm)
 		return;
@@ -120,8 +110,8 @@
 				break;
 			}
 
-			/* 0 and ULONG_MAX entries mean end of backtrace: */
-			if (record == 0 || record == ULONG_MAX)
+			/* 0 entry marks end of backtrace: */
+			if (!record)
 				break;
 		}
 		if (same) {
@@ -139,20 +129,6 @@
 
 	/* Allocted a new one: */
 	memcpy(&latency_record[i], lat, sizeof(struct latency_record));
-}
-
-/*
- * Iterator to store a backtrace into a latency record entry
- */
-static inline void store_stacktrace(struct task_struct *tsk,
-					struct latency_record *lat)
-{
-	struct stack_trace trace;
-
-	memset(&trace, 0, sizeof(trace));
-	trace.max_entries = LT_BACKTRACEDEPTH;
-	trace.entries = &lat->backtrace[0];
-	save_stack_trace_tsk(tsk, &trace);
 }
 
 /**
@@ -191,7 +167,8 @@
 	lat.count = 1;
 	lat.time = usecs;
 	lat.max = usecs;
-	store_stacktrace(tsk, &lat);
+
+	stack_trace_save_tsk(tsk, lat.backtrace, LT_BACKTRACEDEPTH, 0);
 
 	raw_spin_lock_irqsave(&latency_lock, flags);
 
@@ -210,8 +187,8 @@
 				break;
 			}
 
-			/* 0 and ULONG_MAX entries mean end of backtrace: */
-			if (record == 0 || record == ULONG_MAX)
+			/* 0 entry is end of backtrace */
+			if (!record)
 				break;
 		}
 		if (same) {
@@ -252,10 +229,10 @@
 				   lr->count, lr->time, lr->max);
 			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
 				unsigned long bt = lr->backtrace[q];
+
 				if (!bt)
 					break;
-				if (bt == ULONG_MAX)
-					break;
+
 				seq_printf(m, " %ps", (void *)bt);
 			}
 			seq_puts(m, "\n");
@@ -278,22 +255,22 @@
 	return single_open(filp, lstats_show, NULL);
 }
 
-static const struct file_operations lstats_fops = {
-	.open		= lstats_open,
-	.read		= seq_read,
-	.write		= lstats_write,
-	.llseek		= seq_lseek,
-	.release	= single_release,
+static const struct proc_ops lstats_proc_ops = {
+	.proc_open	= lstats_open,
+	.proc_read	= seq_read,
+	.proc_write	= lstats_write,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
 };
 
 static int __init init_lstats_procfs(void)
 {
-	proc_create("latency_stats", 0644, NULL, &lstats_fops);
+	proc_create("latency_stats", 0644, NULL, &lstats_proc_ops);
 	return 0;
 }
 
-int sysctl_latencytop(struct ctl_table *table, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos)
+int sysctl_latencytop(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos)
 {
 	int err;
 

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