sched: wait_bit sample

study/kernel/01-process/00-code/wake_bit/Makefile

@@ -0,0 +1,76 @@
+# ------------------------------------------------------------------------------
+#
+# Makefile for the LDD-LinuxDeviceDrivers.
+#
+# Author: gatieme
+# Create: 2016-07-29 15:50:46
+# Last modified: 2016-07-29 16:10:29
+# Description:
+# 	This program is loaded as a kernel(v2.6.18 or later) module.
+# 	Use "make install" to load it into kernel.
+# 	Use "make remove" to remove the module out of kernel.
+#
+# ------------------------------------------------------------------------------
+
+
+#	my driver description
+DRIVER_VERSION := "1.0.0"
+DRIVER_AUTHOR  := "Gatieme @ AderStep Inc..."
+DRIVER_DESC    := "Linux input module for Elo MultiTouch(MT) devices"
+DRIVER_LICENSE := "Dual BSD/GPL"
+
+
+MODULE_NAME := wake_bit
+#EXTRA_CFLAGS  += -I$(SRC)
+
+
+
+
+
+
+ifneq ($(KERNELRELEASE),)
+
+
+
+
+obj-m := $(MODULE_NAME).o #print_vmarea.o
+
+else
+
+KERNELDIR ?= /lib/modules/$(shell uname -r)/build
+
+PWD := $(shell pwd)
+
+modules:
+	make -C $(KERNELDIR) M=$(PWD) modules
+
+modules_install:
+	make -C $(KERNELDIR) M=$(PWD) modules_install
+
+
+
+insmod:
+	sudo insmod $(MODULE_NAME).ko
+
+reinsmod:
+	sudo rmmod $(MODULE_NAME)
+	sudo insmod $(MODULE_NAME).ko
+
+github:
+	cd $(ROOT) && make github
+
+rmmod:
+	sudo rmmod $(MODULE_NAME)
+
+
+clean:
+	make -C $(KERNELDIR) M=$(PWD) clean
+	rm -f modules.order Module.symvers Module.markers
+
+.PHNOY:
+	modules modules_install clean
+
+
+
+endif
+

study/kernel/01-process/00-code/wake_bit/wake_bit.c

@@ -0,0 +1,55 @@
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/kthread.h>
+#include <linux/wait_bit.h>
+
+#define pr_fmt(fmt)	"WAIT_BIT" fmt
+MODULE_LICENSE("Dual BSD/GPL");
+
+
+#define WAIT_BIT	0
+static unsigned long flag;
+
+
+static int wait_bit_func(void *data)
+{
+        while (!kthread_should_stop()) {
+		wait_on_bit(&flag, WAIT_BIT, TASK_INTERRUPTIBLE);
+
+		pr_info("[%s %d]\n", __func__, __LINE__);
+
+		set_bit(WAIT_BIT, &flag);
+	}
+
+	return 0;
+}
+
+struct task_struct *wait_task = NULL;
+
+static __init int wait_bit_test_init(void)
+{
+	printk("wait_bit module init\n");
+
+	wait_task = kthread_create(wait_bit_func, NULL, "wait_bit_thread");
+	if (wait_task)
+		wake_up_process(wait_task);
+
+	clear_bit(WAIT_BIT, &flag);
+	smp_mb__after_atomic();
+	wake_up_bit(&flag, WAIT_BIT);
+
+	return 0;
+}
+
+static __exit void wait_bit_test_exit(void)
+{
+	if (wait_task)
+		kthread_stop(wait_task);
+
+	printk(KERN_ALERT "wait_bit module exit\n");
+}
+
+
+module_init(wait_bit_test_init);
+module_exit(wait_bit_test_exit);