使用seq_file構建Linux/proc文件驅動程序

Question

爲什麼在使用seq_file構建Linux /proc文件驅動程序時會出現以下錯誤消息？

#include <linux/kernel.h> 
#include <linux/module.h> 
#include <linux/proc_fs.h> 
#include <linux/seq_file.h> 

#define PROC_NAME "iter" 

MODULE_AUTHOR("MS Chaudhari"); 
MODULE_LICENSE("GPL"); 

/* 
    This function is called at the beginning of a sequence. 
    ie, when: 
    - the /proc file is read (first time) 
    - after the function stop (end of sequence) 
*/ 
static void *my_seq_start(struct seq_file *s, loff_t *pos) 
{ 
    static unsigned long counter = 0; 

    // beginning a new sequence 
    if (*pos == 0) 
    { 
     return &counter; 
    } 
    else 
    { 
     *pos = 0; 
     return NULL; 
    } 
} 

/* 
    This function is called after the beginning of a sequence. 
    It's called untill the return is NULL (this ends the sequence). 
*/ 
static void *my_seq_next(struct seq_file *s, void *v, loff_t *pos) 
{ 
    unsigned long *tmp_v = (unsigned long *)v; 
    (*tmp_v)++; 
    (*pos)++; 
    return NULL; 
} 

/* 
    This function is called for each "step" of a sequence 
*/ 

static int my_seq_show(struct seq_file *s, void *v) 
{ 
    loff_t *spos = (loff_t *)v; 

    seq_printf(s, "%Ld\n", *spos); 
    return 0; 
} 

/* 
     This structure gather "function" to manage the sequnce 
*/ 

static struct seq_operation my_seq_ops = 
{ 
    .start = my_seq_start, 
    .next = my_seq_next, 
    .stop = my_seq_stop, 
    .show = my_seq_show 
}; 

/* 
    This function is called when the /proc file is open. 
*/ 
static int my_open(struct inode *inode, struct file *file) 
{ 
    return seq_open(file, &my_seq_ops); 
} 

/* 
    This structure gather "function" that manage the /proc file 
*/ 
static struct file_operations fops = 
{ 
    .owner = THIS_MODULE, 
    .open = my_open, 
    .read = seq_read, 
    .llseek = seq_lseek, 
    .release = seq_release 
}; 


/* 
    This function is called when the module is loaded 
*/ 
int init_module(void) 
{ 
    struct proc_dir_entry *entry; 

    entry = proc_create(PROC_NAME, 0, NULL, &fops); 

// entry = create_entry(PROC_NAME, 0, NULL); 
    if (entry) 
    { 
     entry->proc_fops = &my_file_ops; 
    } 

    return 0; 
} 

/* 
    This function is called when the module is unloaded. 
*/ 
void cleanup_module(void) 
{ 
    remove_proc_entry(PROC_NAME, NULL); 
} 

當我編譯使用make命令，我得到了以下錯誤。

/home/radix/programing/DD/procSeq.c:61:15: error: variable ‘my_seq_ops’ has initializer but incomplete type 
static struct seq_operation my_seq_ops = 
      ^
/home/radix/programing/DD/procSeq.c:63:2: error: unknown field ‘start’ specified in initializer 
    .start = my_seq_start, 
^
/home/radix/programing/DD/procSeq.c:63:2: warning: excess elements in struct initializer [enabled by default] 
/home/radix/programing/DD/procSeq.c:63:2: warning: (near initialization for ‘my_seq_ops’) [enabled by default] 
/home/radix/programing/DD/procSeq.c:64:2: error: unknown field ‘next’ specified in initializer 
    .next = my_seq_next, 
^
/home/radix/programing/DD/procSeq.c:64:2: warning: excess elements in struct initializer [enabled by default] 
/home/radix/programing/DD/procSeq.c:64:2: warning: (near initialization for ‘my_seq_ops’) [enabled by default] 
/home/radix/programing/DD/procSeq.c:65:2: error: unknown field ‘stop’ specified in initializer 
    .stop = my_seq_stop, 
^
/home/radix/programing/DD/procSeq.c:65:10: error: ‘my_seq_stop’ undeclared here (not in a function) 
    .stop = my_seq_stop, 
     ^
/home/radix/programing/DD/procSeq.c:65:2: warning: excess elements in struct initializer [enabled by default] 
    .stop = my_seq_stop, 
^
/home/radix/programing/DD/procSeq.c:65:2: warning: (near initialization for ‘my_seq_ops’) [enabled by default] 
/home/radix/programing/DD/procSeq.c:66:2: error: unknown field ‘show’ specified in initializer 
    .show = my_seq_show 
^
/home/radix/programing/DD/procSeq.c:67:1: warning: excess elements in struct initializer [enabled by default] 
}; 
^ 
/home/radix/programing/DD/procSeq.c:67:1: warning: (near initialization for ‘my_seq_ops’) [enabled by default] 
/home/radix/programing/DD/procSeq.c: In function ‘my_open’: 
/home/radix/programing/DD/procSeq.c:74:2: warning: passing argument 2 of ‘seq_open’ from incompatible pointer type [enabled by default] 
    return seq_open(file, &my_seq_ops); 
^
In file included from /home/radix/programing/DD/procSeq.c:4:0: 
include/linux/seq_file.h:98:5: note: expected ‘const struct seq_operations *’ but argument is of type ‘struct seq_operation *’ 
int seq_open(struct file *, const struct seq_operations *); 
    ^
/home/radix/programing/DD/procSeq.c: In function ‘init_module’: 
/home/radix/programing/DD/procSeq.c:102:8: error: dereferencing pointer to incomplete type 
    entry->proc_fops = &my_file_ops; 
     ^
/home/radix/programing/DD/procSeq.c:102:23: error: ‘my_file_ops’ undeclared (first use in this function) 
    entry->proc_fops = &my_file_ops; 
        ^
/home/radix/programing/DD/procSeq.c:102:23: note: each undeclared identifier is reported only once for each function it appears in 
make[2]: *** [/home/radix/programing/DD/procSeq.o] Error 1 
make[1]: *** [_module_/home/radix/programing/DD] Error 2 
make[1]: Leaving directory `/usr/src/linux-headers-3.13.0-24-generic' 
make: *** [all] Error 2 

對不起，我的代碼很長。

Answer 1

那是因爲沒有struct seq_operation但struct seq_operations