From 9201a2d104103c2271a03d035555d2bef8a625bb Mon Sep 17 00:00:00 2001 From: Simon Marlow Date: Tue, 21 Dec 2010 11:58:07 +0000 Subject: [PATCH] boundTaskExiting: don't set task->stopped unless this is the last call (#4850) The bug in this case was that we had a worker thread making a foreign call which invoked a callback (in this case it was performGC, I think). When the callback ended, boundTaskExiting() was setting task->stopped, but the Task is now per-OS-thread, so it is shared by the worker that made the original foreign call. When the foreign call returned, because task->stopped was set, the worker was not placed on the queue of spare workers. Somehow the worker woke up again, and found the spare_workers queue empty, which lead to a crash. Two bugs here: task->stopped should not have been set by boundTaskExiting (this broke when I split the Task and InCall structs, in 6.12.2), and releaseCapabilityAndQueueWorker() should not be testing task->stopped anyway, because it should only ever be called when task->stopped is false (this is now an assertion). --- rts/Task.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/rts/Task.c b/rts/Task.c index a15758c..a5de804 100644 --- a/rts/Task.c +++ b/rts/Task.c @@ -270,8 +270,6 @@ newBoundTask (void) void boundTaskExiting (Task *task) { - task->stopped = rtsTrue; - #if defined(THREADED_RTS) ASSERT(osThreadId() == task->id); #endif @@ -279,6 +277,14 @@ boundTaskExiting (Task *task) endInCall(task); + // Set task->stopped, but only if this is the last call (#4850). + // Remember that we might have a worker Task that makes a foreign + // call and then a callback, so it can transform into a bound + // Task for the duration of the callback. + if (task->incall == NULL) { + task->stopped = rtsTrue; + } + debugTrace(DEBUG_sched, "task exiting"); } -- 1.7.10.4