From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: [PATCH 3/9] pid: Implement ns_of_pid. Date: Wed, 12 Dec 2007 05:44:01 -0700 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: (Eric W. Biederman's message of "Wed, 12 Dec 2007 05:42:24 -0700") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Andrew Morton Cc: Linux Containers , Oleg Nesterov , Pavel Emelyanov List-Id: containers.vger.kernel.org A current problem with the pid namespace is that it is easy to do pid related work after exit_task_namespaces which drops the nsproxy pointer. However if we are doing pid namespace related work we are always operating on some struct pid which retains the pid_namespace pointer of the pid namespace it was allocated in. So provide ns_of_pid which allows us to find the pid namespace a pid was allocated in. Using this we have the needed infrastructure to do pid namespace related work at anytime we have a struct pid, removing the chance of accidentally having a NULL pointer dereference when accessing current->nsproxy. Signed-off-by: Eric W. Biederman --- include/linux/pid.h | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index f84d532..c4b56c0 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -123,6 +123,17 @@ int next_pidmap(struct pid_namespace *pid_ns, int last); extern struct pid *alloc_pid(struct pid_namespace *ns); extern void FASTCALL(free_pid(struct pid *pid)); +/* ns_of_pid returns the pid namespace in which the specified + * pid was allocated. + */ +static inline struct pid_namespace *ns_of_pid(struct pid *pid) +{ + struct pid_namespace *ns = NULL; + if (pid) + ns = pid->numbers[pid->level].ns; + return ns; +} + /* * the helpers to get the pid's id seen from different namespaces * -- 1.5.3.rc6.17.g1911