proc_pid_unhash —
Unhash /proc/pid entry from the dcache.
struct dentry * proc_pid_unhash (struct task_struct * p);
Drops the /proc/pid dcache entry from the hash chains.
Dropping /proc/pid entries and detach_pid must be synchroneous,
otherwise e.g. /proc/pid/exe might point to the wrong executable,
if the pid value is immediately reused. This is enforced by
- caller must acquire spin_lock(p->proc_lock)
- must be called before detach_pid
- proc_pid_lookup acquires proc_lock, and checks that
the target is not dead by looking at the attach count
of PIDTYPE_PID.