From 73b9ebfe126a4a886ee46cbab637374d7024668a Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 28 Mar 2006 16:11:07 -0800 Subject: [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 Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index 1f16fb1fea22..ddc0df7f8bf5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1214,8 +1214,6 @@ static inline int thread_group_empty(task_t *p) #define delay_group_leader(p) \ (thread_group_leader(p) && !thread_group_empty(p)) -extern void unhash_process(struct task_struct *p); - /* * Protects ->fs, ->files, ->mm, ->ptrace, ->group_info, ->comm, keyring * subscriptions and synchronises with wait4(). Also used in procfs. Also -- cgit v1.2.2