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author | Eric W. Biederman <ebiederm@xmission.com> | 2009-01-07 18:08:46 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-08 08:31:12 -0800 |
commit | f9fb860f67b9542cd78d1558dec7058092b57d8e (patch) | |
tree | 1c14a2d7013df108b6103b7d24b1201fd78b922b /include/linux/pid.h | |
parent | 6af866af34a96fed24a55979a78b6f73bd4e8e87 (diff) | |
download | linux-stable-f9fb860f67b9542cd78d1558dec7058092b57d8e.tar.gz linux-stable-f9fb860f67b9542cd78d1558dec7058092b57d8e.tar.bz2 linux-stable-f9fb860f67b9542cd78d1558dec7058092b57d8e.zip |
pid: implement ns_of_pid
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 <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Bastian Blank <bastian@waldi.eu.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Acked-by: Serge Hallyn <serue@us.ibm.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.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index bb206c56d1f0..49f1c2f66e95 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -123,6 +123,24 @@ extern struct pid *alloc_pid(struct pid_namespace *ns); extern void free_pid(struct pid *pid); /* + * ns_of_pid() returns the pid namespace in which the specified pid was + * allocated. + * + * NOTE: + * ns_of_pid() is expected to be called for a process (task) that has + * an attached 'struct pid' (see attach_pid(), detach_pid()) i.e @pid + * is expected to be non-NULL. If @pid is NULL, caller should handle + * the resulting NULL pid-ns. + */ +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 * * pid_nr() : global id, i.e. the id seen from the init namespace; |