C programming:

I'm kinda sure there's nothing wrong with my function but it kept showing:

This is main(1)...

This is main(2)...

This is main(3)[0]...

this is thread 1 [0]...

this is thread 2 [0]...

this is thread 3 [0]...

This is main(3)[1]...

this is thread 1 [1]...

this is thread 2 [1]...

this is thread 3 [1]...

This is main(3)[2]...

this is thread 1 [2]...

this is thread 2 [2]...

this is thread 3 [2]...

This is main(3)[3]...

Thread 1 is done...

*** glibc detected *** ./t1: double free or corruption (!prev): 0x0000000001371b80 ***

======= Backtrace: =========

/lib64/libc.so.6[0x36f1875f4e]

/lib64/libc.so.6[0x36f1878cf0]

./t1[0x40095f]

The expected output should be:

This is main(1)... This is main(2)... This is main(3)[0]... this is thread 1 [0]... this is thread 2 [0]... this is thread 3 [0]... This is main(3)[1]... this is thread 1 [1]... this is thread 2 [1]... this is thread 3 [1]... This is main(3)[2]... this is thread 1 [2]... this is thread 2 [2]... this is thread 3 [2]... This is main(3)[3]... Thread 1 is done... Thread 2 is done... Thread 3 is done... Begin shutdown... Done with shutdown... 

Here's my code:

#include "t_lib.h" #include

Queue *runningQueue; Queue *readyQueue; ucontext_t *newT; ucontext_t *mainT; TCB *current;

void t_init() { runningQueue = (Queue *)malloc(sizeof(Queue)); readyQueue = (Queue *)malloc(sizeof(Queue)); initQueue(runningQueue); initQueue(readyQueue); mainT = (ucontext_t *) malloc(sizeof(ucontext_t));

getcontext(mainT); /* let mainT be the context of main thread */

Enqueue(runningQueue,createTCB(mainT,0,1)); }

void t_shutdown() { free(runningQueue); free(readyQueue); free(mainT); free(newT); free(current); }

int t_create(void (*fct)(int), int id, int pri) { size_t size = 0x10000; newT = (ucontext_t *) malloc(sizeof(ucontext_t)); getcontext(newT); /* let newT be the context of new thread */ newT->uc_stack.ss_sp = malloc(size); /* new statement */ newT->uc_stack.ss_size = size; newT->uc_stack.ss_flags = 0; newT->uc_link = &runningQueue->front->thread_context; makecontext(newT, (void (*)(void)) fct, 1, id); Enqueue(readyQueue,createTCB(newT,id,pri)); // setcontext(newT); // switch to new one }

void t_terminate() { Dequeue(runningQueue); setcontext(&readyQueue->front->thread_context); }

void t_yield() { current = (TCB *)malloc(sizeof(TCB)); current = runningQueue->front; if (readyQueue->front != NULL) { Enqueue(readyQueue, current); runningQueue->front = readyQueue->front; Dequeue(readyQueue); swapcontext(&readyQueue->rear->thread_context, &runningQueue->front->thread_context); } }

What might be the problem?