The patch titled pids: introduce change_pid() helper has been removed from the -mm tree. Its filename was pids-introduce-change_pid-helper.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: pids: introduce change_pid() helper From: Oleg Nesterov <oleg@xxxxxxxxxx> Based on Eric W. Biederman's idea. Without tasklist_lock held task_session()/task_pgrp() can return NULL if the caller races with setprgp()/setsid() which does detach_pid() + attach_pid(). This can happen even if task == current. Intoduce the new helper, change_pid(), which should be used instead. This way the caller always sees the special pid != NULL, either old or new. Also change the prototype of attach_pid(), it always returns 0 and nobody check the returned value. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/pid.h | 6 ++++-- kernel/pid.c | 21 ++++++++++++++++----- 2 files changed, 20 insertions(+), 7 deletions(-) diff -puN include/linux/pid.h~pids-introduce-change_pid-helper include/linux/pid.h --- a/include/linux/pid.h~pids-introduce-change_pid-helper +++ a/include/linux/pid.h @@ -89,9 +89,11 @@ extern struct pid *get_task_pid(struct t * attach_pid() and detach_pid() must be called with the tasklist_lock * write-held. */ -extern int attach_pid(struct task_struct *task, enum pid_type type, - struct pid *pid); +extern void attach_pid(struct task_struct *task, enum pid_type type, + struct pid *pid); extern void detach_pid(struct task_struct *task, enum pid_type); +extern void change_pid(struct task_struct *task, enum pid_type, + struct pid *pid); extern void transfer_pid(struct task_struct *old, struct task_struct *new, enum pid_type); diff -puN kernel/pid.c~pids-introduce-change_pid-helper kernel/pid.c --- a/kernel/pid.c~pids-introduce-change_pid-helper +++ a/kernel/pid.c @@ -317,7 +317,7 @@ EXPORT_SYMBOL_GPL(find_pid); /* * attach_pid() must be called with the tasklist_lock write-held. */ -int attach_pid(struct task_struct *task, enum pid_type type, +void attach_pid(struct task_struct *task, enum pid_type type, struct pid *pid) { struct pid_link *link; @@ -325,11 +325,10 @@ int attach_pid(struct task_struct *task, link = &task->pids[type]; link->pid = pid; hlist_add_head_rcu(&link->node, &pid->tasks[type]); - - return 0; } -void detach_pid(struct task_struct *task, enum pid_type type) +static void __change_pid(struct task_struct *task, enum pid_type type, + struct pid *new) { struct pid_link *link; struct pid *pid; @@ -339,7 +338,7 @@ void detach_pid(struct task_struct *task pid = link->pid; hlist_del_rcu(&link->node); - link->pid = NULL; + link->pid = new; for (tmp = PIDTYPE_MAX; --tmp >= 0; ) if (!hlist_empty(&pid->tasks[tmp])) @@ -348,6 +347,18 @@ void detach_pid(struct task_struct *task free_pid(pid); } +void detach_pid(struct task_struct *task, enum pid_type type) +{ + __change_pid(task, type, NULL); +} + +void change_pid(struct task_struct *task, enum pid_type type, + struct pid *pid) +{ + __change_pid(task, type, pid); + attach_pid(task, type, pid); +} + /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ void transfer_pid(struct task_struct *old, struct task_struct *new, enum pid_type type) _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch posix-timers-bug-10460-discard-the-pending-signal-when-the-timer-is-destroyed.patch workqueue-remove-redundant-function-invocation.patch put_pid-make-sure-we-dont-free-the-live-pid.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html