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authorEric W. Biederman <ebiederm@xmission.com>2006-09-27 01:51:06 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-27 08:26:19 -0700
commitc18258c6f0848f97e85287f6271c511a092bb784 (patch)
tree16c057a171b7623895ee208459392c1104193b84 /include
parent35fa2048ab13d1be846be612e395c15c200bd51c (diff)
[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 'include')
-rw-r--r--include/linux/pid.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h
index 29960b03bef..93da7e2d9f3 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -76,6 +76,8 @@ extern int FASTCALL(attach_pid(struct task_struct *task,
enum pid_type type, int nr));
extern void FASTCALL(detach_pid(struct task_struct *task, enum pid_type));
+extern void FASTCALL(transfer_pid(struct task_struct *old,
+ struct task_struct *new, enum pid_type));
/*
* look up a PID in the hash table. Must be called with the tasklist_lock