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