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authorOleg Nesterov <oleg@tv-sign.ru>2006-03-28 16:11:07 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-28 18:36:41 -0800
commit73b9ebfe126a4a886ee46cbab637374d7024668a (patch)
treed7ba00d4ce76b49c1569334956cd196b35977a04 /kernel/fork.c
parentc97d98931ac52ef110b62d9b75c6a6f2bfbc1898 (diff)
[PATCH] pidhash: don't count idle threads
fork_idle() does unhash_process() just after copy_process(). Contrary, boot_cpu's idle thread explicitely registers itself for each pid_type with nr = 0. copy_process() already checks p->pid != 0 before process_counts++, I think we can just skip attach_pid() calls and job control inits for idle threads and kill unhash_process(). We don't need to cleanup ->proc_dentry in fork_idle() because with this patch idle threads are never hashed in kernel/pid.c:pid_hash[]. We don't need to hash pid == 0 in pidmap_init(). free_pidmap() is never called with pid == 0 arg, so it will never be reused. So it is still possible to use pid == 0 in any PIDTYPE_xxx namespace from kernel/pid.c's POV. However with this patch we don't hash pid == 0 for PIDTYPE_PID case. We still have have PIDTYPE_PGID/PIDTYPE_SID entries with pid == 0: /sbin/init and kernel threads which don't call daemonize(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c35
1 files changed, 18 insertions, 17 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 74c67629ee6..0c32e28cdc5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1181,25 +1181,26 @@ static task_t *copy_process(unsigned long clone_flags,
*/
p->ioprio = current->ioprio;
- add_parent(p);
- if (unlikely(p->ptrace & PT_PTRACED))
- __ptrace_link(p, current->parent);
-
- if (thread_group_leader(p)) {
- p->signal->tty = current->signal->tty;
- p->signal->pgrp = process_group(current);
- p->signal->session = current->signal->session;
- attach_pid(p, PIDTYPE_PGID, process_group(p));
- attach_pid(p, PIDTYPE_SID, p->signal->session);
-
- list_add_tail(&p->tasks, &init_task.tasks);
- if (p->pid)
+ if (likely(p->pid)) {
+ add_parent(p);
+ if (unlikely(p->ptrace & PT_PTRACED))
+ __ptrace_link(p, current->parent);
+
+ if (thread_group_leader(p)) {
+ p->signal->tty = current->signal->tty;
+ p->signal->pgrp = process_group(current);
+ p->signal->session = current->signal->session;
+ attach_pid(p, PIDTYPE_PGID, process_group(p));
+ attach_pid(p, PIDTYPE_SID, p->signal->session);
+
+ 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++;
}
- attach_pid(p, PIDTYPE_TGID, p->tgid);
- attach_pid(p, PIDTYPE_PID, p->pid);
- nr_threads++;
total_forks++;
spin_unlock(&current->sighand->siglock);
write_unlock_irq(&tasklist_lock);
@@ -1263,7 +1264,7 @@ task_t * __devinit fork_idle(int cpu)
if (!task)
return ERR_PTR(-ENOMEM);
init_idle(task, cpu);
- unhash_process(task);
+
return task;
}