Race condition in master branch

[hsmatulisgoogle]

Here is a race condition I found when debugging on master:

ch_parent_events is created in the worker thread without any signalling, so the parent can attempt to use it before its been defined:

fluent-bit/src/flb_output_thread.c

Lines 176 to 188 in 530866b

	/*
	* Event loop setup between parent engine and this thread
	*
	* - FLB engine uses 'ch_parent_events[1]' to dispatch tasks to this thread
	* - Thread receive message on ch_parent_events[0]
	*
	* The mk_event_channel_create() will attach the pipe read end ch_parent_events[0]
	* to the local event loop 'evl'.
	*/
	ret = mk_event_channel_create(evl,
	&th_ins->ch_parent_events[0],
	&th_ins->ch_parent_events[1],
	th_ins);

fluent-bit/src/flb_output_thread.c

Line 325 in 530866b

n = write(th_ins->ch_parent_events[1], &task, sizeof(struct flb_task *));

I imagine ch_thread_events would have a similar issue

fluent-bit/src/flb_output_thread.c

Lines 198 to 202 in 530866b

	/* Channel used by flush callbacks to notify it return status */
	ret = mk_event_channel_create(evl,
	&th_ins->ch_thread_events[0],
	&th_ins->ch_thread_events[1],
	&event_local);

[edsiper]

ah! good one. So the pipe must be created in the output_thread interface before the thread is created, so it's just shared..

[edsiper]

Fixed in 78b0f6d