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| author | Eric W. Biederman <ebiederm@xmission.com> | 2006-09-27 01:51:06 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-27 08:26:19 -0700 |
| commit | c18258c6f0848f97e85287f6271c511a092bb784 (patch) | |
| tree | 16c057a171b7623895ee208459392c1104193b84 /fs | |
| parent | 35fa2048ab13d1be846be612e395c15c200bd51c (diff) | |
| download | kernel-common-c18258c6f0848f97e85287f6271c511a092bb784.tar.gz kernel-common-c18258c6f0848f97e85287f6271c511a092bb784.tar.bz2 kernel-common-c18258c6f0848f97e85287f6271c511a092bb784.zip | |
[PATCH] pid: Implement transfer_pid and use it to simplify de_thread
In de_thread we move pids from one process to another, a rather ugly case.
The function transfer_pid makes it clear what we are doing, and makes the
action atomic. This is useful we ever want to atomically traverse the
process group and session lists, in a rcu safe manner.
Even if the atomic properties this change should be a win as transfer_pid
should be less code to execute than executing both attach_pid and
detach_pid, and this should make de_thread slightly smaller as only a
single function call needs to be emitted. The only downside is that the
code might be slower to execute as the odds are against transfer_pid being
in cache.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/exec.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/fs/exec.c b/fs/exec.c index 54135df2a966..b7aa3d6422d6 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -696,23 +696,20 @@ static int de_thread(struct task_struct *tsk) */ /* Become a process group leader with the old leader's pid. - * Note: The old leader also uses thispid until release_task + * The old leader becomes a thread of the this thread group. + * Note: The old leader also uses this pid until release_task * is called. Odd but simple and correct. */ detach_pid(current, PIDTYPE_PID); current->pid = leader->pid; attach_pid(current, PIDTYPE_PID, current->pid); - attach_pid(current, PIDTYPE_PGID, current->signal->pgrp); - attach_pid(current, PIDTYPE_SID, current->signal->session); + transfer_pid(leader, current, PIDTYPE_PGID); + transfer_pid(leader, current, PIDTYPE_SID); list_replace_rcu(&leader->tasks, ¤t->tasks); current->group_leader = current; leader->group_leader = current; - /* Reduce leader to a thread */ - detach_pid(leader, PIDTYPE_PGID); - detach_pid(leader, PIDTYPE_SID); - current->exit_signal = SIGCHLD; BUG_ON(leader->exit_state != EXIT_ZOMBIE); |