commit 1ebdaf5788cb7969ee3f853ede4e6e3364343fc0 Author: Nick Mathewson nickm@torproject.org Date: Fri Feb 7 13:13:15 2014 -0500

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. --- changes/bug4345 | 6 +++++- src/common/compat.c | 16 +++++++++++----- 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/changes/bug4345 b/changes/bug4345 index 4975eea..5e650fc 100644 --- a/changes/bug4345 +++ b/changes/bug4345 @@ -1,6 +1,10 @@ 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". diff --git a/src/common/compat.c b/src/common/compat.c index d88c5f9..8a3655e 100644 --- a/src/common/compat.c +++ b/src/common/compat.c @@ -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(); }