Linux 2.6.36以后file_operations和DECLARE_MUTEX 的变化

1， 在include/linux/semaphore.h 中

将#define DECLARE_MUTEX(name) 改成了 #define DEFINE_SEMAPHORE(name)

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,36)

DECLARE_MUTEX(led_sem);

#else

DEFINE_SEMAPHORE(led_sem);

#endif

2， file_operations结构体有了一些变化，它去掉了：

int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);

另外添加了：

long (*fallocate)(struct file *file, int mode, loff_t offset,loff_t len);

这是2.6.36的内核里的定义include/linux/fs.h：

struct file_operations {

struct module *owner;

loff_t (*llseek) (struct file *, loff_t, int);

ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);

ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);

ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);

ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);

int (*readdir) (struct file *, void *, filldir_t);

unsigned int (*poll) (struct file *, struct poll_table_struct *);

//从2.6.36开始删除ioctl(), 2.6.35中有

long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);

long (*compat_ioctl) (struct file *, unsigned int, unsigned long);

int (*mmap) (struct file *, struct vm_area_struct *);

int (*open) (struct inode *, struct file *);

int (*flush) (struct file *, fl_owner_t id);

int (*release) (struct inode *, struct file *);

int (*fsync) (struct file *, int datasync);

int (*aio_fsync) (struct kiocb *, int datasync);

int (*fasync) (int, struct file *, int);

int (*lock) (struct file *, int, struct file_lock *);

ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);

unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

int (*check_flags)(int);

int (*flock) (struct file *, int, struct file_lock *);

ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);

ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);

int (*setlease)(struct file *, long, struct file_lock **);

// long (*fallocate)(struct file *file, int mode, loff_t offset, loff_t len); 从2.6.38内核开始添加该项，2.6.37以下无

};

下面是Linux-2.6.35里的file_operations

struct file_operations {

struct module *owner;

loff_t (*llseek) (struct file *, loff_t, int);

ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);

ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);

ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);

ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);

int (*readdir) (struct file *, void *, filldir_t);

unsigned int (*poll) (struct file *, struct poll_table_struct *);

int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);

long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);

long (*compat_ioctl) (struct file *, unsigned int, unsigned long);

int (*mmap) (struct file *, struct vm_area_struct *);

int (*open) (struct inode *, struct file *);

int (*flush) (struct file *, fl_owner_t id);

int (*release) (struct inode *, struct file *);

int (*fsync) (struct file *, struct dentry *, int datasync);

int (*aio_fsync) (struct kiocb *, int datasync);

int (*fasync) (int, struct file *, int);

int (*lock) (struct file *, int, struct file_lock *);

ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);

unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

int (*check_flags)(int);

int (*flock) (struct file *, int, struct file_lock *);

ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);

ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);

int (*setlease)(struct file *, long, struct file_lock **);

};

make[1]: Entering directory `/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem'
make -C /opt/ti/job_nfs/linux-2.6.37-ti M=/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem ARCH=arm  EXTRA_CFLAGS="-O3 -I -DMAX_POOLS=128" LDDINC=/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem modules
make[2]: Entering directory `/opt/ti/job_nfs/linux-2.6.37-ti'
CC [M]  /opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.o
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:68:2: warning: #warning *** not a warning *** Note: LINUX_VERSION_CODE >= 2.6.26
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:210: warning: type defaults to 'int' in declaration of 'DECLARE_MUTEX'
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:210: warning: parameter names (without types) in function declaration
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:249: error: unknown field 'ioctl' specified in initializer
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:249: warning: initialization from incompatible pointer type
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c: In function 'cmem_seq_stop':
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:819: error: 'cmem_mutex' undeclared (first use in this function)
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:819: error: (Each undeclared identifier is reported only once
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:819: error: for each function it appears in.)
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c: In function 'cmem_seq_start':
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:827: error: 'cmem_mutex' undeclared (first use in this function)
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c: In function 'ioctl':
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:1151: error: 'cmem_mutex' undeclared (first use in this function)
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c: In function 'mmap':
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:1782: error: 'cmem_mutex' undeclared (first use in this function)
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c: In function 'release':
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:1854: error: 'cmem_mutex' undeclared (first use in this function)
make[3]: *** [/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.o] Error 1
make[2]: *** [_module_/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem] Error 2
make[2]: Leaving directory `/opt/ti/job_nfs/linux-2.6.37-ti'
make[1]: *** [default] Error 2
make[1]: Leaving directory `/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem'
make: *** [all] Error 2
dsp@Ubuntu:/opt/ti/job_nfs/examples-03.21.00.04/driver$ ls cmem/
cmem.h  cmemk.c  Makefile

修改：

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
#warning *** not a warning *** Note: LINUX_VERSION_CODE >= 2.6.36
static DEFINE_SEMAPHORE(cmem_mutex);
#else
static DECLARE_MUTEX(cmem_mutex);
#endif

static struct file_operations cmem_fxns = {
.owner = THIS_MODULE,
.open  = open,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
#warning *** not a warning Note: LINUX_VERSION_CODE >= 2.6.36 unlocked_ioctl
    .unlocked_ioctl = cmem_ioctl,
#else
    .ioctl = cmem_ioctl,
#endif
.mmap  = mmap,
.release = release,
};

make[1]: Entering directory `/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem'
make -C /opt/ti/job_nfs/linux-2.6.37-ti M=/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem ARCH=arm  EXTRA_CFLAGS="-O3 -I -DMAX_POOLS=128" LDDINC=/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem modules
make[2]: Entering directory `/opt/ti/job_nfs/linux-2.6.37-ti'
CC [M]  /opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.o
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:44:2: warning: #warning *** not a warning *** Note: LINUX_VERSION_CODE >= 2.6.28
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:70:2: warning: #warning *** not a warning *** Note: LINUX_VERSION_CODE >= 2.6.26
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:214:2: warning: #warning *** not a warning Note: LINUX_VERSION_CODE >= 2.6.36 DEFINE_SEMAPHORE
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:260:2: warning: #warning *** not a warning Note: LINUX_VERSION_CODE >= 2.6.36 unlocked_ioctl
/opt/ti/job_nfs/examples-03.21.00.04/driver/cmem/cmemk.c:261: warning: initialization from incompatible pointer type
Building modules, stage 2.
MODPOST 1 modules
make[1]: Entering directory `/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm'
make -C /opt/ti/job_nfs/linux-2.6.37-ti M=/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm ARCH=arm  EXTRA_CFLAGS="-O3 -I -DMAX_POOLS=" LDDINC=/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm modules
make[2]: Entering directory `/opt/ti/job_nfs/linux-2.6.37-ti'
CC [M]  /opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.o
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:89:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 DEFINE_SEMAPHORE
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:106:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 unlocked_ioctl
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:107: warning: initialization from incompatible pointer type
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c: In function 'dm365mmap_init':
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:300: error: implicit declaration of function 'init_MUTEX_LOCKED'
make[3]: *** [/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.o] Error 1
make[2]: *** [_module_/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm] Error 2
make[2]: Leaving directory `/opt/ti/job_nfs/linux-2.6.37-ti'
make[1]: *** [default] Error 2

在运行时初始化得变化（动态分配）：
以去除：
void init_MUTEX(struct semaphore *sem);void init_MUTEX_LOCKED(struct
semaphore *sem);
可通过以下初始：
void sema_init(struct semaphore *sem, int val);
修改：

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,36)
#warning Note: LINUX_VERSION_CODE >= 2.6.36 sema_init
sema_init(&dm365mmap_reply_mutex, 0);
#else
init_MUTEX_LOCKED(&dm365mmap_reply_mutex);
#endif

make[1]: Entering directory `/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm'
make -C /opt/ti/job_nfs/linux-2.6.37-ti M=/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm ARCH=arm  EXTRA_CFLAGS="-O3 -I -DMAX_POOLS=" LDDINC=/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm modules
make[2]: Entering directory `/opt/ti/job_nfs/linux-2.6.37-ti'
CC [M]  /opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.o
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:89:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 DEFINE_SEMAPHORE
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:106:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 unlocked_ioctl
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:107: warning: initialization from incompatible pointer type
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:174:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 sema_init
/opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.c:308:2: warning: #warning Note: LINUX_VERSION_CODE >= 2.6.36 sema_init
Building modules, stage 2.
MODPOST 1 modules
CC      /opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.mod.o
LD [M]  /opt/ti/job_nfs/examples-03.21.00.04/driver/dm365mm/dm365mmap.ko

ioctl()已使用unlocked_ioctl代替。

但这里不是一个简单的替换，要注意unlocked_ioctl和ioctl的函数原型并不一致。

unlocked_ioctl: long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);

ioctl: int(*ioctl) (struct
inode *,struct file *, unsigned int, unsigned long);

The 'inode' value that was passed to 'ioctl' function is available for use with the 'unlocked_ioctl' function by way of filp->d_entry->d_inode:

long (*unlocked_ioctl) (struct file *filp, unsigned int cmd, unsigned long arg);

...

struct inode *inode = filp->f_path.dentry->d_inode

There is a nice explanation of this at http://lwn.net/Articles/119652/

如：

static long dev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

int index = NUM(file->f_path.dentry->d_inode->i_rdev); /*Which LED*/

.....

}

--------------------------------------

在file_operations 结构体中，会看到许多函数指针所指向的函数都必须传进struct file 结构体指针struct file * 作为参数。struct file 结构体定义在<linux/fs.h> 中，完整如下：

引用

struct file_operations {
struct module *owner;
loff_t (*llseek) (struct file *, loff_t, int);
ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
int (*readdir) (struct file *, void *, filldir_t);
unsigned int (*poll) (struct file *, struct poll_table_struct *);
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
int (*open) (struct inode *, struct file *);
int (*flush) (struct file *, fl_owner_t id);
int (*release) (struct inode *, struct file *);
int (*fsync) (struct file *, int datasync);
int (*aio_fsync) (struct kiocb *, int datasync);
int (*fasync) (int, struct file *, int);
int (*lock) (struct file *, int, struct file_lock *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
int (*check_flags)(int);
int (*flock) (struct file *, int, struct file_lock *);
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
int (*setlease)(struct file *, long, struct file_lock **);
};

struct file {

/*
* fu_list becomes invalid after file_free is called and queued via
* fu_rcuhead for RCU freeing
*/
union {
struct list_head	fu_list;
struct rcu_head 	fu_rcuhead;
} f_u;
struct path		f_path;
#define f_dentry	f_path.dentry
#define f_vfsmnt	f_path.mnt
const struct file_operations	*f_op;
spinlock_t		f_lock;  /* f_ep_links, f_flags, no IRQ */
#ifdef CONFIG_SMP
int			f_sb_list_cpu;
#endif
atomic_long_t		f_count;
unsigned int 		f_flags;
fmode_t			f_mode;
loff_t			f_pos;
struct fown_struct	f_owner;
const struct cred	*f_cred;
struct file_ra_state	f_ra;

u64			f_version;
#ifdef CONFIG_SECURITY
void			*f_security;
#endif
/* needed for tty driver, and maybe others */
void			*private_data;

#ifdef CONFIG_EPOLL
/* Used by fs/eventpoll.c to link all the hooks to this file */
struct list_head	f_ep_links;
#endif /* #ifdef CONFIG_EPOLL */
struct address_space	*f_mapping;
#ifdef CONFIG_DEBUG_WRITECOUNT
unsigned long f_mnt_write_state;
#endif
};

在设备驱动中，struct file 结构体也是一个非常重要的数据结构。注意的是，这里的file 和应用程序中的FILE 流指针没有什么关系，FILE 定义在C 库中，它永远不会出现在内核代码中。

file structure 结构代表一个打开的文件(open file).(打开的文件并没有确切的指定到哪个设备驱动，实际上每个打开的文件都与内核空间中的struct file 结构相关联)。

file structure 结构在调用open 打开一个文件时由内核创建，并会被传递给任一个对这个打开文件进行操作的函数；当所有事情都做完后，会调用close() 关闭掉文件，此时内核释放这个数据结构。

一般地，在内核源码中，struct file 结构体的指针往往写成filp 。

struct file 中的几个重要成员：

mode_t f_mode;

文件模式根据FMMODE_READ 和FMODE_WRITE 位来识别文件是否可读或可写，或是可读可写。在read() 和write() 系统调用中，没有必要对此权限进行检查，因为内核已经在你的系统调用之前已经做了检查。如果文件没有相应的读或写权限，那么如果尝试读写都将被拒绝，驱动程序甚至对此情况毫无知觉。

loff_t f_pos;

此变量表示当前的文件读写位置。loff_t 在所有的平台上都是64 位的变量( long long 型, gcc 专用术语)。驱动程序如果想知道当前在文件中所处位置，那么可以通过读取此变量得知，但是一般地不应直接对此进行更改。通过llseek() 方法可以改变文件位置。

unsigned int f_flags;

这是表示如O_RDONLY, O_NONBLOCK与O_SYNC 这样的标志。一个驱动程序应该检查O_NONBLOCK 标志，以查看是否有非阻塞操作的请求。其它的标志用得比较少。需要注意的是，检查read/write 权限应该是通过检查f_mode 得到而不是f_flags 。所有的标志定义在头文件linux/fcntl.h 中可以看到。

struct file_operations*f_op;

内核安排这个指针作为它的open 实现的一部分，当需要分派什么操作时，会读取它。filp->f_op 因为不会被内核保存起来以在其后之用，所以我们可以改变我们对相关文件的操作，在对文件使用新的操作方法时，我们就会转移到相应调用上。

void *private_data;

在对驱动调用open 方法之前，open() 系统调用会这个指针设置为NULL 。用户可以自由使用这个域，或者对其忽略。可以使用这个域之想分配的数据空间，但必须记得在内核销毁file structure 之前在release 方法里释放掉原来分配的内存。private_data 对于系统调用之间信息的保存会显得非常有用。

struct dentry*f_dentry;

目录入口(dentry) 结构与文件相关。一般的，除了在以filp->f_dentry->d_inode 来访问inode 结构时，我们不太关心dentry 这个结构。