Daniel, thread vs. fork question.

[Michael Snyder <msnyder@redhat.com>]

Hey Daniel,

Got a question concerning the code in 
linux-nat.c::linux_handle_extended_wait.

You've got a PTRACE_EVENT_FORK event, and now you're going to call 
waitpid.  You pull a pid out of a list of stopped pids, and wait for
it using waitpid.  In your comment, you explain that you don't have to
worry about the pid being a clone, because you didn't ask for pids in
the event mask.

But how is this affected by threads, especially NPTL threads?
I've got a fairly simple test-case (modified from pthreads.c,
I'll attach it), in which a child thread calls fork -- but gdb
apparently tries to wait on the main thread (or perhaps the most
recent event thread).  Since that's not the thread that called
fork, waitpid returns -1 with "no child".  Gdb reports:
	waiting for new child: No child processes.

FWIW, I've tried this on both a single-processor and an SMP machine.

Michael