Hi dhiman,
I want to know that you mean i can use
sys_open in my kernel module to open a file through
myfile_open function call?
can a character file be act as a normal file
to store and update that file periodically?
--- "Dhiman, Gaurav" <Gaurav.Dhiman@xxxxxx> wrote:
>
>
> Hi,
>
>
>
> You said that you want to create a file at loading
> time and want to
> remove that file forom file system at unloading
> time, but the code you
> have pasted is actually opening a file at loading
> time, assuming that
> you already have a file in file system.
>
>
>
> For reading or wrting a simple file, do following
> things:
>
> - Create a chracter file (using mknode)
> either dynamically (at
> loading time) or statically by mknode.
>
> - Do not open it at loading time, as you
> are doing right now.
>
> - Open it through your open function
> (myfile_open), which will
> be called from sys_open system call.
>
> - Do not close the file at unloading time,
> as you are doing
> right now.
>
> - Close the file in your function
> (myfile_release), which will
> be called form close system call.
>
> - Do not use filp_open() and filp_close()
> functions at all,
> they are called by open and close system calls
> before the control comes
> to your driver.
>
>
>
> Regards.
>
> Gaurav
>
>
>
> _____
>
> From: kernelnewbies-bounce@xxxxxxxxxxxx
> [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf
> Of linux lover
> Sent: Saturday, September 11, 2004 8:32 PM
> To: kernelnewbies@xxxxxxxxxxxx
> Subject: Device driver query
>
>
>
> i know how to write a character device driver but
> the same will not
> work for
> simple file why? that mean if i create a file
> /root/myfile and want to
> write
> and read to it periodically from a kernel module it
> is not working cause
> i am doing
>
> .....fragment of my code.........
> static struct file_operations myfile_file_operations
> = {
> open: myfile_open,
> release: myfile_release,
> read: myfile_read,
> write: myfile_write,
> };
>
> int init_module(void)
> {
>
> printk("Loading myfile Module\n");
>
> ent = filp_open("/root/myfile", O_RDWR,S_IRUSR |
> S_IWUSR);
> if ( ent == NULL)
> printk(KERN_DEBUG, "Error
> opening file...\n");
> return 0;
> }
>
> void cleanup_module(void)
> {
> printk("Unloading myfile Module\n");
>
> filp_close(ent,NULL);
> }
>
> int myfile_open(struct inode *inodep, struct file
> *filp)
> {
> printk("Opening a file....\n");
> MOD_INC_USE_COUNT;
>
> return 0;
> }
>
> int myfile_release(struct inode *inodep, struct file
> *filp)
> {
> MOD_DEC_USE_COUNT;
> return 0;
> }
>
> I want whenever module is loaded it should create a
> file and when it
> unloaded should
> remove file. but above code is fail to create a file
> and also causing
> problem in unloading
> a module with warning for arg 1 parameter of
> flip_close.
>
> help to write a module to read/write a normal file
> from kernel module.
>
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