Handles all procedures releated to messages of a group device. More...

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/semaphore.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include "types.h"

Include dependency graph for message.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Macros
#define	NO_MSG_PRESENT 0

#define	ALLOC_ERR -2

#define	USER_COPY_ERR -3

#define	SEM_INIT_ERR -4 / @brief Semaphore initialization /

#define	MSG_INVALID_FORMAT -11

#define	MSG_SIZE_ERROR -12

#define	MEMORY_ERROR -13

#define	STORAGE_SIZE_ERR -14

#define	ALLOC_ERR -2

#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	INVALID_IOCTL_COMMAND -1

#define	CHDEV_ALLOC_ERR -22

#define	DEFAULT_GC_RATIO 3

Functions
msg_manager_t *	createMessageManager (const u_int _max_storage_size, const u_int _max_message_size, garbage_collector_t *garbageCollector)
	Allocate and initialize all the members of a 'msg_manager_t' struct. More...

int	writeMessage (msg_t message, msg_manager_t manager)
	write message on a group queue More...

int	readMessage (msg_t dest_buffer, msg_manager_t manager)
	Read a message from the corresponding queue. More...

int	copy_msg_from_user (msg_t kmsg, const char umsg, const ssize_t _size)
	copy a msg_t structure from user-space to kernel-space More...

int	copy_msg_to_user (const msg_t kmsg, __user char ubuffer, const ssize_t _size)
	copy a msg_t structure from kernel-space to user-space More...

void	queueGarbageCollector (struct work_struct *work)
	Remove a message from the queue when it was completely delivered. More...

bool	isDelaySet (const msg_manager_t *manager)
	Check if the message delay is greater than zero on a group. More...

void	delayedMessageCallback (struct timer_list *timer)
	Called when a timer for a delayed message expires. More...

int	queueDelayedMessage (msg_t message, msg_manager_t manager)
	Insert a delayed message into the pending queue. More...

int	revokeDelayedMessage (msg_manager_t *manager)
	Remove all the delayed message from the queue. More...

int	cancelDelay (msg_manager_t *manager)
	Set the delay of messages in the delay queue to zero. More...

Detailed Description

Handles all procedures releated to messages of a group device.

Function Documentation

◆ cancelDelay()

int cancelDelay ( msg_manager_t * manager )

Set the delay of messages in the delay queue to zero.

Parameters

[in] manager The group's message manager

Returns: The number of messages which delay was cancelled

Note: At the moment the function locks the delayed queue, set all timers to zero and unlock the queue. This means that while the function loops through the queue, timer's callback will wait since the queue is locked.

◆ copy_msg_from_user()

int copy_msg_from_user	(	msg_t *	kmsg,
		const char *	umsg,
		const ssize_t	_size
	)

copy a msg_t structure from user-space to kernel-space

Parameters

[out]	kmsg	Kernel-space msg_t
[in]	umsg	User-space msg_t

Return values

0	on success
-EFAULT	if the copy fails

Todo:: Check thread-safety of the function

Note: The kmsg structure must be allocated

◆ copy_msg_to_user()

int copy_msg_to_user	(	const msg_t *	kmsg,
		__user char *	ubuffer,
		const ssize_t	_size
	)

copy a msg_t structure from kernel-space to user-space

Parameters

[in]	kmsg	Kernel-space msg_t
[out]	umsg	User-space buffer

Return values

0	on success
-EFAULT	if the copy fails

Todo:: Check thread-safety of the function

Note: The umsg structure must be allocated

◆ createMessageManager()

msg_manager_t* createMessageManager	(	const u_int	_max_storage_size,
		const u_int	_max_message_size,
		garbage_collector_t *	garbage_collector
	)

Allocate and initialize all the members of a 'msg_manager_t' struct.

Parameters

[in]	_max_message_size	Configurable param
[in]	_max_storage_size	Configurable param
[in]	garbageCollectorFunction	Pointer to the work_struct responsible for garbage collection

Return values

An	'msg_manager_t' pointer to an allocated an initialized 'msg_manager_t' struct
A	NULL pointer in case the 'kmalloc' fails

◆ delayedMessageCallback()

void delayedMessageCallback ( struct timer_list * timer )

Called when a timer for a delayed message expires.

The function simply take the existing 't_message_delayed_deliver' structure, extract the 'msg_t' field and write it into the FIFO queue via the 'writeMessage' function.

Parameters

[in] timer The timer that elasped

Returns: nothing

◆ isDelaySet()

bool isDelaySet ( const msg_manager_t * manager )

Check if the message delay is greater than zero on a group.

Parameters

[in] manager A pointer to the message manager of the group

Note: This function is thread-safe

Return values

true	If the delay is greater than zero
false	If the delay is zero

◆ queueDelayedMessage()

int queueDelayedMessage	(	msg_t *	message,
		msg_manager_t *	manager
	)

Insert a delayed message into the pending queue.

Parameters

[in]	message	The message to insert into the queue
[in]	manager	A pointer to the current msg_manager_t of the group

Return values

0	on success
-1	on error

◆ queueGarbageCollector()

void queueGarbageCollector ( struct work_struct * work )

Remove a message from the queue when it was completely delivered.

Parameters

[in] work The work struct contained inside "msg_manager_t"

Returns: nothing

Todo:: Check if size calculation are done correctly

Note: This function has three critical section, therefore it could be a bottleneck of the module

◆ readMessage()

int readMessage	(	msg_t *	dest_buffer,
		msg_manager_t *	manager
	)

Read a message from the corresponding queue.

Return values

0	on success
1	if no message is present
-1	on critical error

This should't be necessary since the message's sender is automatically added in the list of recipients and, consequently, the 'wasDelivered' function should skip it. However for unknown reason this does not always happens (especially if the message is delayed)

Bug:: : when 'revoke delay' functionality is called, messages trigger this if and will not be delivered

◆ revokeDelayedMessage()

int revokeDelayedMessage ( msg_manager_t * manager )

Remove all the delayed message from the queue.

Parameters

[in] manager The message manager of the group

Note: This function is thread safe with respect to the list of delayed message

Returns: The number of delayed messages which revoked

◆ writeMessage()

int writeMessage	(	msg_t *	message,
		msg_manager_t *	manager
	)

write message on a group queue

Parameters

[in]	message	The data pointed must never be deallocatated
[in]	manager	Pointer to the message manager
[in]	recipients	The head of the linked list containing the thread recipients

Return values

0	on success
STORAGE_SIZE_ERR	if the message does not respect the group's size limits
ALLOC_ERR	if some allocation fails

Note: Must be protected by a write-spinlock to avoid concurrent modification of The recipient data-structure and manager's message queue

Macros

Functions

Detailed Description

Function Documentation

◆ cancelDelay()

◆ copy_msg_from_user()

◆ copy_msg_to_user()

◆ createMessageManager()

◆ delayedMessageCallback()

◆ isDelaySet()

◆ queueDelayedMessage()

◆ queueGarbageCollector()

◆ readMessage()

◆ revokeDelayedMessage()

◆ writeMessage()