commit b3ea3c8e2f3f49f2633c5283a886de650e3cec78 Author: cypherpunks cypherpunks@torproject.org Date: Thu Jul 23 11:28:31 2015 +0200

Switch order of unblocking threads and releasing the mutex.

According to POSIX, the mutex must be locked by the thread calling the signal functions to ensure predictable scheduling behavior.

Found the issue using Helgrind which gave the warning `dubious: associated lock is not held by any thread`. --- changes/bug16644 | 3 +++ src/common/workqueue.c | 8 ++++---- 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/changes/bug16644 b/changes/bug16644 new file mode 100644 index 0000000..f7126bd --- /dev/null +++ b/changes/bug16644 @@ -0,0 +1,3 @@ + o Minor bugfixes (relay): + - Unblock threads before releasing the mutex to ensure predictable + scheduling behavior. Fixes bug 16644; bugfix on 0.2.6.3-alpha. diff --git a/src/common/workqueue.c b/src/common/workqueue.c index 3f9a063..cf63634 100644 --- a/src/common/workqueue.c +++ b/src/common/workqueue.c @@ -293,10 +293,10 @@ threadpool_queue_work(threadpool_t *pool,

TOR_TAILQ_INSERT_TAIL(&pool->work, ent, next_work);

- tor_mutex_release(&pool->lock); - tor_cond_signal_one(&pool->condition);

+ tor_mutex_release(&pool->lock); + return ent; }

@@ -345,10 +345,10 @@ threadpool_queue_update(threadpool_t *pool, pool->update_fn = fn; ++pool->generation;

- tor_mutex_release(&pool->lock); - tor_cond_signal_all(&pool->condition);

+ tor_mutex_release(&pool->lock); + if (old_args) { for (i = 0; i < n_threads; ++i) { if (old_args[i] && old_args_free_fn)