Deadlock example in C using MQX Lite

vivian_dandan — Wed, 18 Nov 2015 22:35:29 GMT

Hi there,

I'm pretty new to multithread, but I need to write a test case for Deadlock condition. Saw an example using mutex, but with pthread.

Thread 1:

pthread_mutex_lock(&m1);

pthread_mutex_lock(&m2);

pthread_mutex_unlock(&m2);

pthread_mutex_unlock(&m1);

Thread 2:

pthread_mutex_lock(&m2);

pthread_mutex_lock(&m1);

pthread_mutex_unlock(&m1);

pthread_mutex_unlock(&m2);

How should I re-write it here?

Thanks a lot!

Vivian

Re: Deadlock example in C using MQX Lite

soledad — Wed, 18 Nov 2015 23:01:25 GMT

Hello Dandan,

Please check the below example, I hope this helps.

Have a great day,
Sol

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/* ###################################################################

** Filename : mqx_tasks.c

** Project : ProcessorExpert

** Processor : MK20DX128VLH5

** Component : Events

** Version : Driver 01.00

** Compiler : GNU C Compiler

** Date/Time : 2013-02-11, 11:06, # CodeGen: 0

** Abstract :

** This is user's event module.

** Put your event handler code here.

** Settings :

** Contents :

** Task1_task - void Task1_task(uint32_t task_init_data);

** Task2_task - void Task2_task(uint32_t task_init_data);

** ###################################################################*/

/*!

** @file mqx_tasks.c

** @version 01.00

** @date 2013-02-11, 11:06, # CodeGen: 0

** @brief

** This is user's event module.

** Put your event handler code here.

/*!

** @addtogroup mqx_tasks_module mqx_tasks module documentation

** @{

/* MODULE mqx_tasks */

#include "Cpu.h"

#include "Events.h"

#include "mqx_tasks.h"

/* User includes (#include below this line is not maintained by Processor Expert) */

#include "mutex.h"

MUTEX_STRUCT print_mutex;

** ===================================================================

** Event : Task1_task (module mqx_tasks)

** Component : Task1 [MQXLite_task]

** Description :

** MQX task routine. The routine is generated into mqx_tasks.c

** file.

** Parameters :

** NAME - DESCRIPTION

** task_init_data -

** Returns : Nothing

** ===================================================================

void main_task(uint32_t task_init_data)

{

_task_id task_id;

MUTEX_ATTR_STRUCT mutexattr;

const char* string1 = "Hello from Print task 1\n";

const char* string2 = "Hello from Print task 2\n";

/* Initialize mutex attributes */

if (_mutatr_init(&mutexattr) != MQX_OK) {

printf("Initialize mutex attributes failed.\n");

_task_block();

}

/* Initialize the mutex */

if (_mutex_init(&print_mutex, &mutexattr) != MQX_OK) {

printf("Initialize print mutex failed.\n");

_task_block();

}

/* Create the print tasks */

printf(" - Creating print1_task");

task_id = _task_create_at(0, PRINT1_TASK, (uint_32)string1, print1_task_stack, PRINT1_TASK_STACK_SIZE);

if (task_id == MQX_NULL_TASK_ID) {

printf("...failed\n");

}

printf(" - Creating print2_task");

task_id = _task_create_at(0, PRINT2_TASK, (uint_32)string2, print2_task_stack, PRINT2_TASK_STACK_SIZE);

if (task_id == MQX_NULL_TASK_ID) {

printf("...failed\n");

}

_task_block();

}

** ===================================================================

** Event : print1_task (module mqx_tasks)

** Component : Task2 [MQXLite_task]

** Description :

** MQX task routine. This task prints a message. It uses a mutex to

** ensure I/O is not interleaved.

** Parameters :

** NAME - DESCRIPTION

** task_init_data -

** Returns : Nothing

** ===================================================================

void print1_task(uint32_t task_init_data)

{

while(TRUE) {

if (_mutex_lock(&print_mutex) != MQX_OK) {

printf("Mutex lock failed.\n");

_task_block();

}

puts((char *)task_init_data);

_time_delay_ticks(10);

_mutex_unlock(&print_mutex);

}

** ===================================================================

** Event : print2_task (module mqx_tasks)

** Component : Task3 [MQXLite_task]

** Description :

** MQX task routine. This task prints a message. It uses a mutex to

** ensure I/O is not interleaved.

** Parameters :

** NAME - DESCRIPTION

** task_init_data -

** Returns : Nothing

** ===================================================================

void print2_task(uint32_t task_init_data)

{

while(TRUE) {

if (_mutex_lock(&print_mutex) != MQX_OK) {

printf("Mutex lock failed.\n");

_task_block();

}

puts((char *)task_init_data);

_time_delay_ticks(10);

_mutex_unlock(&print_mutex);

}

/* END mqx_tasks */

/*!

** @}

** ###################################################################

** This file was created by Processor Expert 10.0.12 [05.05]

** for the Freescale Kinetis series of microcontrollers.

** ###################################################################

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Deadlock example in C using MQX Lite

Re: Deadlock example in C using MQX Lite