Commit 1ebdaf57 authored by Nick Mathewson's avatar Nick Mathewson 🤹
Browse files

More hacking around spawn_func issues 

This time, we use a pthread_attr to make sure that if pthread_create
succeeds, the thread is successfully detached.

This probably isn't the big thing going on with 4345, since it'd be
a bit weird for pthread_detach to be failing.  But it's worth
getting it right.
parent 85b46d57

changes/bug4345

+5 −1
Original line number Diff line number Diff line 
  o Minor bugfixes:

    - Check return code on spawn_func() in cpuworker code, so that we don't

      think we've spawned a nonworking cpuworker and write junk to it

      forever. Fix for bug 4345; bugfix on all released Tor versions.

      forever. Fix related to bug 4345; bugfix on all released Tor versions.

      Found by "skruffy".



    - Use a pthread_attr to make sure that spawn_func() cannot return

      an error while at the same time launching a thread. Fix related

      to bug 4345; bugfix on all released Tor versions. Reported by

      "cypherpunks".

src/common/compat.c

+11 −5
Original line number Diff line number Diff line
@@ -2248,6 +2248,12 @@ tor_pthread_helper_fn(void *_data) 
  func(arg);

  return NULL;

}

/**

 * A pthread attribute to make threads start detached.

 */

static pthread_attr_t attr_detached;

/** True iff we've called tor_threads_init() */

static int threads_initialized = 0;

#endif



/** Minimalist interface to run a void function in the background.  On
@@ -2271,12 +2277,12 @@ spawn_func(void (*func)(void *), void *data) 
#elif defined(USE_PTHREADS)

  pthread_t thread;

  tor_pthread_data_t *d;

  if (PREDICT_UNLIKELY(!threads_initialized))

    tor_threads_init();

  d = tor_malloc(sizeof(tor_pthread_data_t));

  d->data = data;

  d->func = func;

  if (pthread_create(&thread,NULL,tor_pthread_helper_fn,d))

    return -1;

  if (pthread_detach(thread))

  if (pthread_create(&thread,&attr_detached,tor_pthread_helper_fn,d))

    return -1;

  return 0;

#else
@@ -2633,8 +2639,6 @@ tor_get_thread_id(void) 
 * "reentrant" mutexes (i.e., once we can re-lock if we're already holding

 * them.) */

static pthread_mutexattr_t attr_reentrant;

/** True iff we've called tor_threads_init() */

static int threads_initialized = 0;

/** Initialize <b>mutex</b> so it can be locked.  Every mutex must be set

 * up with tor_mutex_init() or tor_mutex_new(); not both. */

void
@@ -2778,6 +2782,8 @@ tor_threads_init(void) 
  if (!threads_initialized) {

    pthread_mutexattr_init(&attr_reentrant);

    pthread_mutexattr_settype(&attr_reentrant, PTHREAD_MUTEX_RECURSIVE);

    tor_assert(0==pthread_attr_init(&attr_detached));

    tor_assert(0==pthread_attr_setdetachstate(&attr_detached, 1));

    threads_initialized = 1;

    set_main_thread();

  }