No need to synchronize linux_schedtail with linux_proc_init.
p->p_emuldata is properly initialized in the time when the child can run.

Do not set p->p_emuldata to NULL when the process is exiting.
It does not make any sense and only costs 2 mutex operations.

Do not lock emul_data to unlock it on the very next line.
Comment on possible race while there.

Reparent all procs that are part of a threading group but not its leaders
to init and SIGCHLD init to finish the zombies off. This fixes zombies
left after opera's exit. [1]

There is no need to lock p_em in the linux_proc_init CLONE_THREAD
case because the process cannot change the address of the p_em->shared
because its currently running this code path.
Move assigning of em->shared outside emul_shared_lock.

Noticed by: Scott Robbins <scottro@nyc.rr.com> [1]
Submitted by: rdivacky