inline int scull_open(int tid, inode i, file filp)
{
scull_dev dev;
dev = container_of(i);
filp = dev;
if (down_interruptible())
return -ERESTARTSYS;
__X__ = 2; /* check mutual exclusion */
scull_trim(dev); /* ignore errors */
assert(__X__ >= 2); /* check mutual exclusion */
up();
return 0; /* success */
}
int scull_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev; /* device information */
dev = container_of(inode->i_cdev, struct scull_dev, cdev);
filp->private_data = dev; /* for other methods */
/* now trim to 0 the length of the device if open was write-only */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
if (down_interruptible(&dev->sem))
return -ERESTARTSYS;
scull_trim(dev); /* ignore errors */
up(&dev->sem);
}
return 0; /* success */
}
int scull_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev; /* device information */
dev = container_of(inode->i_cdev, struct scull_dev, cdev);
filp->private_data = dev; /* for other methods */
/* If the device was opened write-only, trim it to a length of 0. */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
if (mutex_lock_interruptible(&dev->mutex))
return -ERESTARTSYS;
scull_trim(dev); /* Ignore errors. */
mutex_unlock(&dev->mutex);
}
return 0;
}
int scull_open( struct inode *inode, struct file *filp )
{
struct scull_dev *dev;
dev = container_of( inode->i_cdev, struct scull_dev, cdev );
filp->private_data = dev;
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY )
{
if ( down_interruptible( &dev->sem ) )
return(-ERESTARTSYS);
scull_trim( dev );
up( &dev->sem );
}
return(0);
}
/*
* The cleanup function is used to handle initialization failures as well.
* Thefore, it must be careful to work correctly even if some of the items
* have not been initialized
*/
void scull_cleanup_module(void)
{
int i;
dev_t devno = MKDEV(scull_major, scull_minor);
/* Get rid of our char dev entries */
if (scull_devices) {
for (i = 0; i < scull_nr_devs; i++) {
scull_trim(scull_devices + i);
cdev_del(&scull_devices[i].cdev);
}
kfree(scull_devices);
}
/* cleanup_module is never called if registering failed */
unregister_chrdev_region(devno, scull_nr_devs);
}
int scull_s_open (struct inode *inode, struct file *filp)
{
Scull_Dev *dev = &scull_s_device; /* device information */
int num = NUM(inode->i_rdev);
if (num > 0) return -ENODEV; /* 1 device only */
if (scull_s_count) return -EBUSY; /* already open */
scull_s_count++;
/* then, everything else is copied from the bare scull device */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY)
scull_trim(dev);
filp->private_data = dev;
MOD_INC_USE_COUNT;
return 0; /* success */
}
void cleanup_module(void)
{
int i;
unregister_chrdev(scull_major, "scull");
#ifdef SCULL_USE_PROC
proc_unregister(&proc_root, scull_proc_entry.low_ino);
#endif
for (i=0; i<scull_nr_devs; i++)
scull_trim(scull_devices+i);
kfree(scull_devices);
/* and call the cleanup functions for friend devices */
scull_p_cleanup();
scull_access_cleanup();
}
/* In scull_open, the fop_array is used according to TYPE(dev) */
int scull_open(struct inode *inode, struct file *filp)
{
Scull_Dev *dev; /* device information */
int num = NUM(inode->i_rdev);
int type = TYPE(inode->i_rdev);
/*
* the type and num values are only valid if we are not using devfs.
* However, since we use them to retrieve the device pointer, we
* don't need them with devfs as filp->private_data is already
* initialized
*/
/*
* If private data is not valid, we are not using devfs
* so use the type (from minor nr.) to select a new f_op
*/
if (!filp->private_data && type) {
if (type > SCULL_MAX_TYPE) return -ENODEV;
filp->f_op = scull_fop_array[type];
return filp->f_op->open(inode, filp); /* dispatch to specific open */
}
/* type 0, check the device number (unless private_data valid) */
dev = (Scull_Dev *)filp->private_data;
if (!dev) {
if (num >= scull_nr_devs) return -ENODEV;
dev = &scull_devices[num];
filp->private_data = dev; /* for other methods */
}
MOD_INC_USE_COUNT; /* Before we maybe sleep */
/* now trim to 0 the length of the device if open was write-only */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
if (down_interruptible(&dev->sem)) {
MOD_DEC_USE_COUNT;
return -ERESTARTSYS;
}
scull_trim(dev); /* ignore errors */
up(&dev->sem);
}
return 0; /* success */
}
int scull_open(struct inode *inodp, struct file *filp)
{
struct Scull_dev *lscull_dev;
#ifdef PRINTK
printk(KERN_INFO"Begin:%s\n",__func__);
#endif
lscull_dev = container_of(inodp->i_cdev,struct Scull_dev,cdev);
if(!lscull_dev)
{
#ifdef PRINTK
printk(KERN_ERR"End E:Error in container_of\n");
#endif
}
filp->private_data = lscull_dev;
//check for access mode
if((filp->f_flags & O_ACCMODE)==O_RDONLY)
{
#ifdef PRINTK
printk(KERN_INFO"File opened in read only mode\n");
#endif
}
//trim if in write only mode
if((filp->f_flags & O_ACCMODE)==O_WRONLY)
{
#ifdef PRINTK
printk(KERN_INFO"File opened in write only mode\n");
#endif
scull_trim(scull_dev);
}
filp->private_data = lscull_dev;
#ifdef PRINTK
printk(KERN_INFO"End:%s\n",__func__);
#endif
return 0;
}
/*
* open and close
*/
int sculloc_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev; /* device info */
/* Find the device */
dev = container_of(inode->i_cdev, struct scullc_dev, cdev);
/* now trim to 0 the length of the device if open was write-only */
if ((filp->f_flags & O_ACCMODE) == O_WRONLY)
{
if (down_interruptible(&dev->sem))
return -ERESTARTSYS;
scull_trim(dev); /* ignore errrs */
up(&dev->sem);
}
/* and use filp->private_data to point to the device data */
filp->private_data = dev;
return 0; /* success */
}
int scull_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev;
dev = container_of(inode->i_cdev, struct scull_dev, cdev);
if(!dev)
{
printk(KERN_ALERT "In scull_open(), dev is NULL");
return 0;
}
filp->private_data = dev;
if((filp->f_flags & O_ACCMODE) == O_WRONLY){
scull_trim(dev);
}
#ifdef __DEBUG_INFO
printk(KERN_ALERT "In scull_open()\n");
#endif
return 0;
}
int scull_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev; /* device information */
/*
* 调用container_of宏，通过cdev成员得到包含该cdev的scull_dev结构,然后保存在flip文件中
*/
dev = container_of(inode->i_cdev, struct scull_dev, cdev);
filp->private_data = dev; /* for other methods */
/* now trim to 0 the length of the device if open was write-only */
/* 如果scull设备文件是以只写的方式打开，则要调用scull_trim将scull设备清空 */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
/*
* 进行加锁解锁操作，进行互斥
*/
if (down_interruptible(&dev->sem))
return -ERESTARTSYS;
scull_trim(dev); /* ignore errors */
up(&dev->sem);
}
return 0; /* success */
}
/*
* The cleanup function is used to handle initialization failures as well.
* Thefore, it must be careful to work correctly even if some of the items
* have not been initialized
*/
void scull_cleanup_module(void)
{
int i;
dev_t devno = MKDEV(scull_major, scull_minor);
/* Remove proc entry */
remove_proc_entry("scullmem", NULL /* parent dir */);
/* Remove seq_file interfaced proc entry */
remove_proc_entry("scullseq", NULL);
/* Get rid of our char dev entries */
if (scull_devices) {
for (i = 0; i < scull_nr_devs; i++) {
scull_trim(scull_devices + i);
cdev_del(&scull_devices[i].cdev);
}
kfree(scull_devices);
}
/* cleanup_module is never called if registering failed */
unregister_chrdev_region(devno, scull_nr_devs);
}
static int scull_u_open(struct inode *inode, struct file *filp) {
struct scull_dev *dev = &scull_u_device;
spin_lock(&scull_u_lock);
if (scull_u_count &&
(scull_u_owner != current->uid) &&
(scull_u_owner != current->euid) &&
!capable(CAP_DAC_OVERRIDE)) {
spin_unlock(&scull_u_lock);
return -EBUSY;
}
if (scull_u_count == 0)
scull_u_owner = current->uid;
scull_u_count++;
spin_unlock(&scull_u_lock);
if ((filp->f_flags & O_ACCMODE) == O_WRONLY)
scull_trim(dev);
filp->private_data = dev;
return 0;
}
static void scull_cleanup_module(void)
{
int i;
dev_t dev = MKDEV(scull_major, scull_minor);
#ifdef __DEBUG_INFO
printk(KERN_ALERT "In clean up !!!/n");
#endif
if(scull_devices != NULL){
printk(KERN_ALERT "In clean up !!!/n");
for(i = 0; i < scull_num; i++)
{
scull_trim(scull_devices + i);
cdev_del(&(scull_devices[i].cdev));
}
kfree(scull_devices);
}else{
printk(KERN_ALERT "In clean up,devices is NULL !!!/n");
}
unregister_chrdev_region(dev, scull_num);
}
void scull_cleanup_module(void)
{
int i;
dev_t devno = MKDEV(scull_major, scull_minor);
/* Get rid of our char dev entries */
if (scull_devices) {
for (i = 0; i < scull_nr_devs; i++) {
scull_trim(scull_devices + i);
cdev_del(&scull_devices[i].cdev);
}
kfree(scull_devices);
}
#ifdef SCULL_DEBUG /* use proc only if debugging */
scull_remove_proc();
#endif
/* cleanup_module is never called if registering failed */
unregister_chrdev_region(devno, scull_nr_devs);
/* and call the cleanup functions for friend devices */
//scull_p_cleanup();
//scull_access_cleanup();
printk(KERN_ALERT "Scull device removed.. \n");
}
static int scull_w_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev = &scull_w_device; /* device information */
spin_lock(&scull_w_lock);
while (! scull_w_available()) {
spin_unlock(&scull_w_lock);
if (filp->f_flags & O_NONBLOCK) return -EAGAIN;
if (wait_event_interruptible (scull_w_wait, scull_w_available()))
return -ERESTARTSYS; /* tell the fs layer to handle it */
spin_lock(&scull_w_lock);
}
if (scull_w_count == 0)
scull_w_owner = current->cred->uid.val; /* grab it */
scull_w_count++;
spin_unlock(&scull_w_lock);
/* then, everything else is copied from the bare scull device */
if ((filp->f_flags & O_ACCMODE) == O_WRONLY)
scull_trim(dev);
filp->private_data = dev;
return 0; /* success */
}
static int scull_u_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev = &scull_u_device; /* device information */
spin_lock_init(&scull_u_lock); /* Initialize lock */
spin_lock(&scull_u_lock); /* spin till lock is acquired */
if (scull_u_count && (scull_u_owner != current_uid().val) && /* allow user */
(scull_u_owner != current_euid().val) && /* allow whoever did su */
!capable(CAP_DAC_OVERRIDE)) { /* still allow root */
spin_unlock(&scull_u_lock);
return -EBUSY; /* -EPERM would confuse user */
}
if (scull_u_count == 0)
scull_u_owner = current_uid().val; /* grab it */
scull_u_count++;
spin_unlock(&scull_u_lock);
/* then everything else is copied from the bare scull device */
if ((filp->f_flags & O_ACCMODE) == O_WRONLY)
scull_trim(dev);
filp->private_data = dev;
return 0;
}
void scull_cleanup_module(void)
{
int i;
dev_t devno = MKDEV(scull_major, scull_minor);
if (scull_devices) {
for (i = 0; i < scull_nr_devs; i++) {
scull_trim(scull_devices + i);//???
cdev_del(&scull_devices[i].cdev);
}
kfree(scull_devices);
}
//#ifdef SCULL_DEBUG
scull_remove_proc();
//#endif
unregister_chrdev_region(devno, scull_nr_devs);
// scull_p_cleanup();
// scull_access_cleanup();
}
//限制每次只能由一个进程打开
//只允许一个进程打开设备
static int scull_s_open(struct inode *inode, struct file *filp)
{
struct scull_dev *dev = &scull_s_device; /* 设备信息 */
/*
此设备中维护一个atomic_t变量 称为scull_s_available 该变量值初始化值为1，表明该设备真正可用
open 会减小并测试scull_s_available 并在其他进程打开该设备时拒绝访问
*/
//int atomic_dec_and_test(atomic_t *v); 原子类型的变量v原子地减1，并判断结果是否为0，如果为0，返回真，否则返回假
if (! atomic_dec_and_test (&scull_s_available))
{
//void atomic_inc(atomic_t *v); 原子类型变量v原子地增加1。
atomic_inc(&scull_s_available);
return -EBUSY; /* 已打开 */
}
/* 然后 从裸的scull设备中复制所有其他数据 */
if ( (filp->f_flags & O_ACCMODE) == O_WRONLY)
{
scull_trim(dev);
}
filp->private_data = dev;
return 0; /* 成功 */
}
static int char_reg_setup_cdev (void)
{
int retval;
int temp = 0;
struct device *class_dev;
dev_t devid = MKDEV (helloworld_major, helloworld_minor);
scull_devices = kmalloc(helloworld_nr_device * sizeof (struct scull_dev),\
GFP_KERNEL);
memset((char *)scull_devices, 0,\
helloworld_nr_device * sizeof(struct scull_dev));
for (; temp < helloworld_nr_device; temp++) {
scull_devices[temp].quantum = quantum;
scull_devices[temp].qset = qset;
scull_devices[temp].size = 0;
cdev_init(&scull_devices[temp].cdev, &helloworld_fops);
scull_devices[temp].cdev.ops = &helloworld_fops;
scull_devices[temp].cdev.owner = THIS_MODULE;
}
retval= cdev_add(&scull_devices[temp].cdev, devid, helloworld_nr_device);
if (retval < 0) {
DEBUG (1, "err_cdev_add.");
goto err_cdev_add;
}
helloworld_class = class_create(THIS_MODULE, "hbgk_class");
if (IS_ERR(helloworld_class)) {
retval = PTR_ERR(helloworld_class);
DEBUG (1, "err_class_create.");
goto err_class_create;
}
for (temp = 0; temp < helloworld_nr_device; temp++) {
class_dev = device_create(helloworld_class, NULL, MKDEV(helloworld_major, temp), NULL,
"hbgk_device%d", temp);
//class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
if (IS_ERR(class_dev)) {
retval= PTR_ERR(class_dev);
DEBUG (1, "err_device_create %d", temp);
goto err_device_create;
}
}
#if 0
cdev_p= cdev_alloc();
if (!cdev_p) {
DEBUG(1, "cdev_alloc failed\n");
goto out;
}
cdev_p->owner = THIS_MODULE;
cdev_p->ops = &helloworld_fops;
err = cdev_add(cdev_p, devid, HELLOWORLD_MAX_DEVICE);
if (err < 0) {
DEBUG (1, "cdev_add fialed.\n");
goto err_cdev_add;
}
#endif
return 0;
err_device_create:
class_destroy(helloworld_class);
err_class_create:
for (temp = 0; temp < helloworld_nr_device; temp++) {
cdev_del(&scull_devices[temp].cdev);
scull_trim(&scull_devices[temp]);
}
err_cdev_add:
kfree (scull_devices);
scull_devices = NULL;
return retval;
}
/*
* The cleanup function is used to handle initialization failures as well.
* Thefore, it must be careful to work correctly even if some of the items
* have not been initialized
*/
inline void scull_cleanup_module(void)
{
scull_dev dev;
scull_trim(dev);
}