Lesson06: Implement kernel module for test kernel time functions and timers

06-TimeManagement/Makefile

@@ -0,0 +1,5 @@
+obj-m+=omod6_kern_time.o
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean

06-TimeManagement/chkpatch.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+curdir=$(pwd)
+cd ~/kernel/linux
+./scripts/checkpatch.pl --no-tree --no-signoff --ignore LONG_LINE,LONG_LINE_COMMENT,LONG_LINE_STRING -f $curdir/$1
+cd $curdir

06-TimeManagement/omod6_kern_time.c

@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: AFL-3.0
+/*
+ * Copyright (C) 2018
+ * Author: Oleg Khokhlov <[email protected]>
+ *
+ * SysFS kernel module for test kernel timing functions
+ *
+ * doc links:
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+
+#include <linux/jiffies.h>
+#include <linux/ktime.h>
+#include <linux/timer.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+
+
+
+//Internal Kernel API (Time Management):
+
+//1. Implement kernel module with API in sysfs or procfs, which is able to:
+// - return time (in seconds) passed since previous read;
+// - return absolute time of previous reading;
+// - periodically print some message to log, make period adjustable;
+
+// --------------- MODULE PARAMETERS DESCRIPTION -------------------
+//int iParam;
+//module_param(iParam, int, 0);
+//MODULE_PARM_DESC(iParam, "iParam: ReturnCode");
+
+//char *sParam = "Default";
+//module_param(sParam, charp, 0);
+//MODULE_PARM_DESC(sParam, "sParam: string parameter");
+
+//------------ GLOBAL MODULE DATA ---------------------
+static struct class *attr_class;
+
+#define SysFS_DIR_NAME   "omod6"
+#define SysFS_ATTR_NAME  "ktime"
+
+uint32_t ModCallCount;
+uint32_t LastCallTimeSec;
+uint32_t LastCall_dT;
+uint32_t LastCallTicks;
+
+uint32_t TimerInterval;
+uint32_t TimerCounter;
+uint32_t TimerStartTick;
+
+char LogMessage[256];
+
+uint32_t GetTimeStamp(void)
+{
+	return (uint32_t) (ktime_to_ms(ktime_get_real()) / 1000);
+}
+
+uint32_t GetTickCount(void)
+{
+	return (uint32_t) (get_jiffies_64() * 1000 / HZ);
+}
+
+
+//--------------- SysFS read/write functions ----------------------
+
+static ssize_t ktime_show(struct class *cl,
+			struct class_attribute *attr,
+			char *buf)
+{
+	int L;
+	uint32_t TS, dT, T;
+	struct rtc_time tm;
+
+	T = GetTickCount();
+	TS = GetTimeStamp();
+	dT = TS - LastCallTimeSec;
+
+	if (dT == 0)
+		dT = LastCall_dT;
+	else
+		LastCall_dT = dT;
+
+	LastCallTicks = T;
+
+	ModCallCount++;
+
+	sprintf(buf, "ktime (%u ticks, %u HZ):\n", (uint32_t)get_jiffies_64(), HZ);
+	sprintf(strchr(buf, 0), "%u module call\n", ModCallCount);
+	sprintf(strchr(buf, 0), "%u sec from last call\n", dT);
+	rtc_time64_to_tm(TS, &tm);
+	//https://ru.wikipedia.org/wiki/Time.h
+	sprintf(strchr(buf, 0), "%u sec curr abs time from Epoch (%d.%02d.%02d, %02d:%02d:%02d)\n", TS,
+		tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+	sprintf(strchr(buf, 0), "%u sec prev call abs time from Epoch\n", LastCallTimeSec);
+	sprintf(strchr(buf, 0), "%u ms - Timer Interval\n", TimerInterval);
+	sprintf(strchr(buf, 0), "%u times timer called\n", TimerCounter);
+
+	LastCallTimeSec = TS;
+
+	L = strlen(buf);
+	return L;
+}
+
+// Kernel Timer object
+struct timer_list MyTimer;
+
+//
+// Kernel Timer Function. Run in interrupt context! Called only once after start/mod
+//
+void KernelTimerFunc(struct timer_list *t)
+{
+	uint32_t T, dT;
+
+	TimerCounter++;
+	T = GetTickCount();
+	dT = T - TimerStartTick;
+	pr_info("omod6 timer[%u]: %s (delay = %u ms)\n", TimerCounter, LogMessage, dT);
+}
+
+
+static ssize_t ktime_store(struct class *cl,
+			struct class_attribute *attr,
+			const char *buf, size_t count)
+{
+	int interval = 0;
+	char *cp;
+	int n;
+
+	if (sscanf(buf, "%d", &interval) == 1) {
+		cp = strchr(buf, ' ');
+		if (cp) {
+			while (*cp == ' ')
+				cp++;
+			for (n = 0; n < sizeof(LogMessage) - 1; n++) {
+				if (*cp < ' ')
+					break;
+				LogMessage[n] = *cp++;
+			}
+			LogMessage[n] = 0;
+		}
+	}
+
+	pr_info("omod6 store (%d, \'%s\')\n", interval, LogMessage);
+
+	TimerInterval = interval;
+
+	// start, stop or reconfig timer
+	if (interval == 0) {
+		if (timer_pending(&MyTimer)) {
+			del_timer(&MyTimer);
+			pr_info("omod6 Timer disabled\n");
+		}
+	} else {
+		unsigned long expired = get_jiffies_64() + interval * HZ / 1000;
+		mod_timer(&MyTimer, expired);
+		TimerStartTick = GetTickCount();
+		pr_info("omod6 Timer started (interval=%u)\n", interval);
+	}
+	return count;
+}
+
+static struct class_attribute class_attr_ktime = {
+	.attr = { .name = SysFS_ATTR_NAME, .mode = 0666 },
+	.show = ktime_show,
+	.store = ktime_store
+};
+
+
+static int __init omod_init(void)
+{
+	int ret;
+
+	attr_class = class_create(THIS_MODULE, SysFS_DIR_NAME);
+	if (attr_class == NULL) {
+		pr_err("omod6: error creating sysfs class\n");
+		return -EEXIST;
+	}
+
+	ret = class_create_file(attr_class, &class_attr_ktime);
+	if (ret) {
+		pr_err("omod6: error creating sysfs class attribute\n");
+		class_destroy(attr_class);
+		return ret;
+	}
+
+	timer_setup(&MyTimer, KernelTimerFunc, 0);
+
+	pr_info("omod6 Kernel time function test module started.\n");
+	LastCallTimeSec = GetTimeStamp();
+	return 0;
+}
+
+static void __exit omod_exit(void)
+{
+	class_remove_file(attr_class, &class_attr_ktime);
+	class_destroy(attr_class);
+
+	pr_info("omod6 module normal shutdown.\n");
+}
+
+module_init(omod_init);
+module_exit(omod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Oleg Khokhlov");
+MODULE_DESCRIPTION("OlegH Lesson06 module: test kernel time funcs");
+MODULE_VERSION("0.2");
+

06-TimeManagement/omod6_kern_time.chklog

@@ -0,0 +1,8 @@
+bash$ 
+bash$ ./chkpatch.sh omod6_kern_time.c
+total: 0 errors, 0 warnings, 204 lines checked
+
+/home/olegh/gl-kernel-training-2018/06-TimeManagement/omod6_kern_time.c has no obvious style problems and is ready for submission.
+
+NOTE: Ignored message types: LONG_LINE LONG_LINE_COMMENT LONG_LINE_STRING
+bash$ 

06-TimeManagement/omod6_kern_time.log

@@ -0,0 +1,76 @@
+bash$ 
+bash$ sudo dmesg -C
+bash$ sudo insmod omod6_kern_time.ko
+bash$ dmesg
+[164257.292896] omod6 Kernel time function test module started.
+bash$ 
+bash$ cat /sys/class/omod6/ktime 
+ktime (40995296 ticks, 250 HZ):
+1 module call
+24 sec from last call
+1542096090 sec curr abs time from Epoch (year:2018)
+1542096066 sec prev call abs time from Epoch
+0 ms - Timer Interval
+0 times timer called
+bash$ 
+bash$ 
+bash$ cat /sys/class/omod6/ktime 
+ktime (40997586 ticks, 250 HZ):
+2 module call
+9 sec from last call
+1542096099 sec curr abs time from Epoch (year:2018)
+1542096090 sec prev call abs time from Epoch
+0 ms - Timer Interval
+0 times timer called
+bash$ 
+bash$ 
+bash$ echo "5000 Hello from timer" > /sys/class/omod6/ktime
+bash$ 
+bash$ dmesg
+[164257.292896] omod6 Kernel time function test module started.
+[164312.443489] omod6 store (5000, 'Hello')
+[164312.443495] omod6 Timer started (interval=5000)
+bash$ 
+bash$ dmesg
+[164257.292896] omod6 Kernel time function test module started.
+[164312.443489] omod6 store (5000, 'Hello')
+[164312.443495] omod6 Timer started (interval=5000)
+[164317.680785] omod6 timer[1]: Hello (delay = 5240 ms)
+bash$ 
+bash$ 
+bash$ cat /sys/class/omod6/ktime 
+ktime (41007134 ticks, 250 HZ):
+3 module call
+38 sec from last call
+1542096137 sec curr abs time from Epoch (year:2018)
+1542096099 sec prev call abs time from Epoch
+5000 ms - Timer Interval
+1 times timer called
+bash$ 
+bash$ 
+bash$ echo "10000 Hello from timer2" > /sys/class/omod6/ktime
+bash$ echo "0 Hello from timer2" > /sys/class/omod6/ktime
+bash$ dmesg
+[164257.292896] omod6 Kernel time function test module started.
+[164312.443489] omod6 store (5000, 'Hello')
+[164312.443495] omod6 Timer started (interval=5000)
+[164317.680785] omod6 timer[1]: Hello (delay = 5240 ms)
+[164348.845400] omod6 store (10000, 'Hello')
+[164348.845406] omod6 Timer started (interval=10000)
+[164353.156345] omod6 store (0, 'Hello')
+[164353.156350] omod6 Timer disabled
+bash$ 
+bash$ 
+bash$ cat /sys/class/omod6/ktime 
+ktime (41018014 ticks, 250 HZ):
+4 module call
+44 sec from last call
+1542096181 sec curr abs time from Epoch (year:2018)
+1542096137 sec prev call abs time from Epoch
+0 ms - Timer Interval
+1 times timer called
+bash$ 
+bash$ 
+bash$ sudo rmmod omod6_kern_time
+bash$ 
+bash$ 

06-TimeManagement/omod6_kern_time2.chklog

@@ -0,0 +1,30 @@
+bash$ 
+bash$ ./chkpatch.sh omod6_kern_time.c
+WARNING: Prefer kstrto<type> to single variable sscanf
+#138: FILE: /home/olegh/gl-kernel-training-2018/06-TimeManagement/omod6_kern_time.c:138:
++	if (sscanf(buf, "%d", &interval) == 1) {
++		cp = strchr(buf, ' ');
++		if (cp) {
++			while (*cp == ' ')
++				cp++;
++			for (n = 0; n < sizeof(LogMessage) - 1; n++) {
++				if (*cp < ' ')
++					break;
++				LogMessage[n] = *cp++;
++			}
++			LogMessage[n] = 0;
++		}
++	}
+
+total: 0 errors, 1 warnings, 222 lines checked
+
+NOTE: For some of the reported defects, checkpatch may be able to
+      mechanically convert to the typical style using --fix or --fix-inplace.
+
+/home/olegh/gl-kernel-training-2018/06-TimeManagement/omod6_kern_time.c has style problems, please review.
+
+NOTE: Ignored message types: LONG_LINE LONG_LINE_COMMENT LONG_LINE_STRING
+
+NOTE: If any of the errors are false positives, please report
+      them to the maintainer, see CHECKPATCH in MAINTAINERS.
+bash$ 

06-TimeManagement/omod6_kern_time2.log

@@ -0,0 +1,35 @@
+bash$ 
+bash$ 
+bash$ sudo insmod omod6_kern_time.ko
+bash$ cat /sys/class/omod6/ktime 
+ktime (50320923 ticks, 250 HZ):
+1 module call
+4 sec from last call
+1542138138 sec curr abs time from Epoch (2018.11.13, 19:42:18)
+1542138134 sec prev call abs time from Epoch
+0 ms - Timer Interval
+0 times timer called
+bash$ 
+bash$ 
+bash$ echo "2000 Hello from module timer!" > /sys/class/omod6/ktime
+bash$ 
+bash$ cat /sys/class/omod6/ktime 
+ktime (50325075 ticks, 250 HZ):
+2 module call
+17 sec from last call
+1542138155 sec curr abs time from Epoch (2018.11.13, 19:42:35)
+1542138138 sec prev call abs time from Epoch
+2000 ms - Timer Interval
+1 times timer called
+bash$ 
+bash$ 
+bash$ dmesg
+[201578.642960] omod6 Kernel time function test module started.
+[201593.096793] omod6 store (2000, 'Hello from module timer!')
+[201593.096800] omod6 Timer started (interval=2000)
+[201595.113490] omod6 timer[1]: Hello from module timer! (delay = 2020 ms)
+bash$ 
+bash$ 
+bash$ sudo rmmod omod6_kern_time
+bash$ 
+bash$