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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/pid.c
parentc97d98931ac52ef110b62d9b75c6a6f2bfbc1898 (diff)
downloadlwn-73b9ebfe126a4a886ee46cbab637374d7024668a.tar.gz
lwn-73b9ebfe126a4a886ee46cbab637374d7024668a.zip
[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/pid.c')
-rw-r--r--kernel/pid.c10
1 files changed, 1 insertions, 9 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index 7781d9999058..a9f2dfd006d2 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -247,16 +247,8 @@ void __init pidhash_init(void)
void __init pidmap_init(void)
{
- int i;
-
pidmap_array->page = (void *)get_zeroed_page(GFP_KERNEL);
+ /* Reserve PID 0. We never call free_pidmap(0) */
set_bit(0, pidmap_array->page);
atomic_dec(&pidmap_array->nr_free);
-
- /*
- * Allocate PID 0, and hash it via all PID types:
- */
-
- for (i = 0; i < PIDTYPE_MAX; i++)
- attach_pid(current, i, 0);
}