base: fix race in multiple lock.unlock() calls

Fixes #2122
2016-10-07 19:59:18 +02:00 · 2016-10-07 19:59:18 +02:00 · c99729093a
parent 9013ca5364
commit c99729093a
1 changed files with 5 additions and 1 deletions
--- a/repos/base/src/lib/base/lock.cc
+++ b/repos/base/src/lib/base/lock.cc
@ -146,12 +146,16 @@ void Cancelable_lock::unlock()

 		/* transfer lock ownership to next applicant and wake him up */
 		_owner = *next_owner;
+
+		/* make copy since _owner may change outside spinlock ! */
+		Applicant owner = *next_owner;
+
 		if (_last_applicant == next_owner)
 			_last_applicant = &_owner;

 		spinlock_unlock(&_spinlock_state);

-		_owner.wake_up();
+		owner.wake_up();

 	} else {