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Switch order of unblocking threads and releasing the mutex.

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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`.
This commit is contained in:
cypherpunks 2015-07-23 11:28:31 +02:00 committed by Nick Mathewson
parent 5721627517
commit b3ea3c8e2f
2 changed files with 7 additions and 4 deletions
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3
changes/bug16644 Normal file
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@ -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.

8
src/common/workqueue.c
View File

@ -293,10 +293,10 @@ threadpool_queue_work(threadpool_t *pool,
TOR_TAILQ_INSERT_TAIL(&pool->work, ent, next_work); TOR_TAILQ_INSERT_TAIL(&pool->work, ent, next_work);
tor_mutex_release(&pool->lock);
tor_cond_signal_one(&pool->condition); tor_cond_signal_one(&pool->condition);
tor_mutex_release(&pool->lock);
return ent; return ent;
} }
@ -345,10 +345,10 @@ threadpool_queue_update(threadpool_t *pool,
pool->update_fn = fn; pool->update_fn = fn;
++pool->generation; ++pool->generation;
tor_mutex_release(&pool->lock);
tor_cond_signal_all(&pool->condition); tor_cond_signal_all(&pool->condition);
tor_mutex_release(&pool->lock);
if (old_args) { if (old_args) {
for (i = 0; i < n_threads; ++i) { for (i = 0; i < n_threads; ++i) {
if (old_args[i] && old_args_free_fn) if (old_args[i] && old_args_free_fn)