android_kernel_xiaomi_sm8350/include/linux/pid.h
Oleg Nesterov 47e65328a7 [PATCH] pids: kill PIDTYPE_TGID
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>
2006-03-28 18:36:44 -08:00

54 lines
1.3 KiB
C

#ifndef _LINUX_PID_H
#define _LINUX_PID_H
enum pid_type
{
PIDTYPE_PID,
PIDTYPE_PGID,
PIDTYPE_SID,
PIDTYPE_MAX
};
struct pid
{
/* Try to keep pid_chain in the same cacheline as nr for find_pid */
int nr;
struct hlist_node pid_chain;
/* list of pids with the same nr, only one of them is in the hash */
struct list_head pid_list;
};
#define pid_task(elem, type) \
list_entry(elem, struct task_struct, pids[type].pid_list)
/*
* attach_pid() and detach_pid() must be called with the tasklist_lock
* write-held.
*/
extern int FASTCALL(attach_pid(struct task_struct *task, enum pid_type type, int nr));
extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
/*
* look up a PID in the hash table. Must be called with the tasklist_lock
* held.
*/
extern struct pid *FASTCALL(find_pid(enum pid_type, int));
extern int alloc_pidmap(void);
extern void FASTCALL(free_pidmap(int));
#define do_each_task_pid(who, type, task) \
if ((task = find_task_by_pid_type(type, who))) { \
prefetch((task)->pids[type].pid_list.next); \
do {
#define while_each_task_pid(who, type, task) \
} while (task = pid_task((task)->pids[type].pid_list.next,\
type), \
prefetch((task)->pids[type].pid_list.next), \
hlist_unhashed(&(task)->pids[type].pid_chain)); \
} \
#endif /* _LINUX_PID_H */