From mboxrd@z Thu Jan 1 00:00:00 1970 From: sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org Subject: Re: [PATCH 3/9] pid: Implement ns_of_pid. Date: Wed, 12 Dec 2007 16:59:45 -0800 Message-ID: <20071213005945.GB27896@us.ibm.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: 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: "Eric W. Biederman" Cc: Linux Containers , Andrew Morton , Oleg Nesterov , Pavel Emelyanov List-Id: containers.vger.kernel.org Eric W. Biederman [ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org] wrote: | | 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. Yep. | | 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) My patch refers to this function as pid_active_pid_ns() - I have been meaning to send that out on top of your signals patch. Since a pid has many namespaces, we have been using 'active pid ns' to refer to this ns. Even your next patch modifies task_active_pid_ns() to use this. So can we rename this functio to pid_active_pid_ns() ? | +{ | + 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