group_manager.h File Reference

Handles all procedures releated to file operation issued on a group device. More...

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/semaphore.h>
#include <linux/ioctl.h>
#include <linux/string.h>
#include <linux/idr.h>
#include <linux/errno.h>
#include <linux/cred.h>
#include "message.h"

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Macros
#define	INVALID_IOCTL_COMMAND   -1
#define	ALLOC_ERR   -2
#define	MEM_ACCESS_ERR   -5
#define	CLASS_EXISTS   -10
#define	CLASS_ERR   -11
#define	DEV_CREATION_ERR   -12
#define	CDEV_ALLOC_ERR   -13
#define	EMPTY_LIST   -20
#define	NODE_NOT_FOUND   -21
#define	CHDEV_ALLOC_ERR   -22
#define	GROUP_MAX_MINORS   255
#define	DEVICE_NAME_SIZE   64
#define	DEFAULT_MSG_SIZE   256
#define	DEFAULT_STORAGE_SIZE   1024
#define	IOCTL_GET_GROUP_DESC   _IOR('Q', 1, group_t*)
#define	IOCTL_SET_STRICT_MODE   _IOW('Q', 101, bool)
#define	IOCTL_CHANGE_OWNER   _IOW('Q', 102, uid_t)
#define	IOCTL_SET_SEND_DELAY   _IOW('Y', 0, long)
#define	IOCTL_REVOKE_DELAYED_MESSAGES   _IO('Y', 1)
#define	IOCTL_CANCEL_DELAY   _IO('Y', 2)
#define	IOCTL_SLEEP_ON_BARRIER   _IO('Z', 0)
#define	IOCTL_AWAKE_BARRIER   _IO('Z', 1)
#define	GROUP_CLASS_NAME   "group_synch"

Functions
void	initParticipants (group_data *grp_data)
	Initialize group_data participants' structures. More...
int	installGroupClass (void)
	Install the global 'group_device_class'. More...
int	registerGroupDevice (group_data *grp_data, struct device *parent)
	register a group device More...
void	unregisterGroupDevice (group_data *grp_data, bool flag)
	unregister a group device More...
int	copy_group_t_from_user (__user group_t *user_group, group_t *kern_group)
	Copy a 'group_t' structure to kernel space. More...

Variables
struct class *	group_device_class

Detailed Description

Handles all procedures releated to file operation issued on a group device.

Function Documentation

copy_group_t_from_user()

int copy_group_t_from_user	(	__user group_t *	user_group,
		group_t *	kern_group
	)

Copy a 'group_t' structure to kernel space.

Parameters

[in]	user_group	Pointer to a userspace 'group_t' structure
[out]	kern_group	Destination that will contain the 'group_t' structure

Return values

0	on success
MEM_ACCESS_ERR	if the user memory is not valid for the kernel
USER_COPY_ERR	if there was error while copying user data to kernel
ALLOC_ERR	if there was some meory allocation error

initParticipants()

void initParticipants ( group_data *  grp_data )

inline

Initialize group_data participants' structures.

Parameters

[in]

grp_data

Pointer to the device's group_data structure

Returns

nothing

installGroupClass()

int installGroupClass

(

)

Install the global 'group_device_class'.

Return values

0	if the class already exists
CLASS_ERR	If the class cannot be installed
CLASS_EXISTS	If the class already exists

registerGroupDevice()

int registerGroupDevice	(	group_data *	grp_data,
		struct device *	parent
	)

register a group device

Parameters

[in]	grp_data	The group data descriptor
[in]	parent	device parent (usually 'main_device')

Return values

0	on success
CHDEV_ALLOC_ERR	If the char device allocation fails
ALLOC_ERR	If some memory allocation fails
DEV_CREATION_ERR	If the char device creation fails

Note

Charter device creation This should be perfomed after all the all the necessary data structures are allocated since, immediately after 'cdev_add', the device becomes live and starts to respond to requests

unregisterGroupDevice()

void unregisterGroupDevice	(	group_data *	grp_data,
		bool	flag
	)

unregister a group device

Parameters

[in]

grp_data

The group data descriptor

Returns

nothing

Note

This guarantees that cdev device will no longer be able to be opened, however any cdevs already open will remain and their fops will still be callable even after cdev_del returns. For this reason the 'initialized' flag of a group will be set to zero

Todo:

: Check if this causes starvation