Programming Forums - pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?!

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- - pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?! (http://www.programmingforums.org/showthread.php?t=15805)

pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?!

From the following source code

int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)

{

volatile pthread_descr self = thread_self();



__pthread_lock(&cond->__c_lock, self);

enqueue(&cond->__c_waiting, self);

__pthread_unlock(&cond->__c_lock);

pthread_mutex_unlock(mutex);

suspend_with_cancellation(self);

pthread_mutex_lock(mutex);

/* This is a cancellation point */

if (THREAD_GETMEM(self, p_canceled)

&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {

/* Remove ourselves from the waiting queue if we're still on it */

__pthread_lock(&cond->__c_lock, self);

remove_from_queue(&cond->__c_waiting, self);

__pthread_unlock(&cond->__c_lock);

pthread_exit(PTHREAD_CANCELED);

}

return 0;

}

it seems that when a thread gets canceled while waiting for cond it performs
pthread_mutex_lock(mutex);
...
pthread_exit(PTHREAD_CANCELED);

and leaves mutex locked?!
so anothe thread is potentially deadlocked?!
I tried to look in the source for pthread_exit() if and when the mutex is released but I didn't figure out!

Re: pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?!

You might want to check out how to post code properly before you get flamed.

>BstrucT

Re: pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?!

So may be to prevent this the correct usage is

  pthread_mutex_lock(mutex);

  pthread_cleanup_push(pthread_mutex_unlock,mutex);

  while (...) pthread_cond_wait(cond,mutex); 

......

  pthread_cleanup_pop();

  pthread_mutex_unlock(mutex);

what you think?

Re: pthread_cond_wait if cancelled leaves mutex locked deadlocking other threads?!

Noted your comment to thread as unpleasant.

I apologize for the rude reply I have made to your thread, that was dumb. But it is important to note how to format code properly, as I have been tapped accross the fingers for the same mistake, a few times. I wasn't trying to be rude, just trying to give you a heads up man. My apologies if it went down wrong.