id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	field_blocks	field_dependson	field_seealso
281	printf functions are overserialized	Jiri Svoboda		"Prior to changeset:mainline,791 vprintf() (uspace/lib/c/generic/io/vprintf.c) guarded the call to printf_core() with async_serialize(). Now it uses a ''global'' fibril mutex.

This is slightly better, but still not good enough. Mutual exclusion, if any, should only be done per stream. The global lock incurs unnecessary (and potentially dangerous) dependencies between fibrils writing to completely different streams (e.g. to console and to a network socket, when we have sockfs).

Actually, do we really want to ensure mutual exclusion for printf (on a specific stream)? AFAICT this is just a workaround for the fact that stream I/O functions are not fibril-safe.

If we add the missing locking to stream I/O functions, we can drop the mutex from vprintf() altogether. The worst that could happen when multiple fibrils called printf() in parallel would be that the outputs would be intermixed, which is, IMO, acceptable.

If an application needs to ensure that output of different fibrils is not intermixed, it should employ its own locking.
"	enhancement	new	major		helenos/lib/c