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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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11
include/linux/sched.h
View file

@ -752,6 +752,7 @@ struct task_struct {
/* PID/PID hash table linkage. */
struct pid pids[PIDTYPE_MAX];
struct list_head thread_group;
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
@ -1192,13 +1193,17 @@ extern void wait_task_inactive(task_t * p);
#define while_each_thread(g, t) \
while ((t = next_thread(t)) != g)
extern task_t * FASTCALL(next_thread(const task_t *p));
#define thread_group_leader(p) (p->pid == p->tgid)
static inline task_t *next_thread(task_t *p)
{
return list_entry(rcu_dereference(p->thread_group.next),
task_t, thread_group);
}
static inline int thread_group_empty(task_t *p)
{
return list_empty(&p->pids[PIDTYPE_TGID].pid_list);
return list_empty(&p->thread_group);
}
#define delay_group_leader(p) \