From: Eric W. Biederman <ebiederm@xmission.com>
Date: Wed, 27 Sep 2006 08:51:06 +0000 (-0700)
Subject: [PATCH] pid: Implement transfer_pid and use it to simplify de_thread
X-Git-Tag: v2.6.19-rc1~910
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c18258c6f0848f97e85287f6271c511a092bb784;p=pandora-kernel.git

[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>
---

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