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authorOleg Nesterov <oleg@tv-sign.ru>2006-03-28 16:11:25 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-28 18:36:44 -0800
commit47e65328a7b1cdfc4e3102e50d60faf94ebba7d3 (patch)
tree78e00a5321cca87767806a91e623e71b5c6637c7
parent88531f725bd52e37a7be726860e4ff3f09031d89 (diff)
downloadop-kernel-dev-47e65328a7b1cdfc4e3102e50d60faf94ebba7d3.zip
op-kernel-dev-47e65328a7b1cdfc4e3102e50d60faf94ebba7d3.tar.gz
[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>
-rw-r--r--include/linux/pid.h1
-rw-r--r--include/linux/sched.h11
-rw-r--r--kernel/exit.c10
-rw-r--r--kernel/fork.c4
4 files changed, 12 insertions, 14 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h
index 099e70e..5b9082c 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -4,7 +4,6 @@
enum pid_type
{
PIDTYPE_PID,
- PIDTYPE_TGID,
PIDTYPE_PGID,
PIDTYPE_SID,
PIDTYPE_MAX
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a913fca..99855f6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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) \
diff --git a/kernel/exit.c b/kernel/exit.c
index aea23e7..22399ca 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -51,7 +51,6 @@ static void __unhash_process(struct task_struct *p)
{
nr_threads--;
detach_pid(p, PIDTYPE_PID);
- detach_pid(p, PIDTYPE_TGID);
if (thread_group_leader(p)) {
detach_pid(p, PIDTYPE_PGID);
detach_pid(p, PIDTYPE_SID);
@@ -59,7 +58,7 @@ static void __unhash_process(struct task_struct *p)
list_del_init(&p->tasks);
__get_cpu_var(process_counts)--;
}
-
+ list_del_rcu(&p->thread_group);
remove_parent(p);
}
@@ -964,13 +963,6 @@ asmlinkage long sys_exit(int error_code)
do_exit((error_code&0xff)<<8);
}
-task_t fastcall *next_thread(const task_t *p)
-{
- return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID);
-}
-
-EXPORT_SYMBOL(next_thread);
-
/*
* Take down every thread in the group. This is called by fatal signals
* as well as by sys_exit_group (below).
diff --git a/kernel/fork.c b/kernel/fork.c
index 12cdd9f..bc551efb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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++;
}
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