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authorOleg Nesterov <oleg@tv-sign.ru>2008-04-30 11:54:26 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 19:29:48 +0400
commit24336eaeecea860b2a82530e07c80bc7e0558b73 (patch)
tree12a34660f732e12ba18262083c1a2eea5a824f6a /include/linux/pid.h
parent65450cebc6a2efde80ed45514f727e6e4dc1eafd (diff)
downloadlinux-24336eaeecea860b2a82530e07c80bc7e0558b73.tar.xz
pids: introduce change_pid() helper
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@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/pid.h')
-rw-r--r--include/linux/pid.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h
index c7980810eb09..8d199033c0ca 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -89,9 +89,11 @@ extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type);
* 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);