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* The parent/group dead semaphores are now released a bit earlier to make

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wait_for_child() hanging less probable - there is a general problem with
  this code, though, as we need to have a dedicated free counter for the
  semaphore to remove all race conditions.
* Also, test fork_3-1 still sometimes fails because the thread is still
  available to the public for a short time, even after its death entry
  has been collected.
* Added a TODO in the code for these issues.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@18529 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2006-08-17 21:45:37 +00:00
parent 73a56f1bac
commit 79dd3d935a
1 changed files with 9 additions and 8 deletions
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17
src/system/kernel/thread.c
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@ -855,6 +855,7 @@ thread_exit2(void *_args)
remove_thread_from_team(team_get_kernel_team(), args.thread);
RELEASE_TEAM_LOCK();
// TODO: this needs to be done earlier, so that this thread cannot be found on its last trip
GRAB_THREAD_LOCK();
hash_remove(sThreadHash, args.thread);
sUsedThreads--;
@ -905,7 +906,7 @@ thread_exit(void)
struct death_entry *death = NULL;
thread_id mainParentThread = -1;
bool deleteTeam = false;
sem_id cachedDeathSem = -1, parentDeadSem = -1, groupDeadSem = -1;
sem_id cachedDeathSem = -1;
status_t status;
struct thread_debug_info debugInfo;
team_id teamID = team->id;
@ -1005,8 +1006,13 @@ thread_exit(void)
} else
death = NULL;
parentDeadSem = parent->dead_children.sem;
groupDeadSem = team->group->dead_child_sem;
// notify listeners that a new death entry is available
// TODO: should that be moved to handle_signal() (for SIGCHLD)?
// TODO: B_RELEASE_ALL opens up a race condition with wait_for_child().
release_sem_etc(parent->dead_children.sem, 0,
B_RELEASE_ALL | B_DO_NOT_RESCHEDULE);
release_sem_etc(team->group->dead_child_sem, 0,
B_RELEASE_ALL | B_DO_NOT_RESCHEDULE);
}
team_remove_team(team, &freeGroup);
@ -1021,11 +1027,6 @@ thread_exit(void)
// delete the team if we're its main thread
if (deleteTeam) {
// notify listeners that a new death entry is available
// ToDo: should that be moved to handle_signal() (for SIGCHLD)?
release_sem_etc(parentDeadSem, 0, B_RELEASE_ALL | B_DO_NOT_RESCHEDULE);
release_sem_etc(groupDeadSem, 0, B_RELEASE_ALL | B_DO_NOT_RESCHEDULE);
team_delete_process_group(freeGroup);
team_delete_team(team);