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[PATCH] pids: kill PIDTYPE_TGID

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This patch kills PIDTYPE_TGID pid_type thus saving one hash table in
kernel/pid.c and speeding up subthreads create/destroy a bit.  It is also a
preparation for the further tref/pids rework.

This patch adds 'struct list_head thread_group' to 'struct task_struct'
instead.

We don't detach group leader from PIDTYPE_PID namespace until another
thread inherits it's ->pid == ->tgid, so we are safe wrt premature
free_pidmap(->tgid) call.

Currently there are no users of find_task_by_pid_type(PIDTYPE_TGID).
Should the need arise, we can use find_task_by_pid()->group_leader.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-By: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov
2006-03-28 16:11:25 -08:00
committed by Linus Torvalds
parent 88531f725b
commit 47e65328a7
4 changed files with 12 additions and 14 deletions
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4
kernel/fork.c
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@@ -1112,6 +1112,7 @@ static task_t *copy_process(unsigned long clone_flags,
* We dont wake it up yet.
*/
p->group_leader = p;
INIT_LIST_HEAD(&p->thread_group);
INIT_LIST_HEAD(&p->ptrace_children);
INIT_LIST_HEAD(&p->ptrace_list);
@@ -1165,7 +1166,9 @@ static task_t *copy_process(unsigned long clone_flags,
retval = -EAGAIN;
goto bad_fork_cleanup_namespace;
}
p->group_leader = current->group_leader;
list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
if (current->signal->group_stop_count > 0) {
/*
@@ -1213,7 +1216,6 @@ static task_t *copy_process(unsigned long clone_flags,
list_add_tail(&p->tasks, &init_task.tasks);
__get_cpu_var(process_counts)++;
}
attach_pid(p, PIDTYPE_TGID, p->tgid);
attach_pid(p, PIDTYPE_PID, p->pid);
nr_threads++;
}