Commit:     2894d650cd9715d00ca196c711265819ef6ebd2d
Parent:     baf8f0f82dd79e374bf6fa9e996393df2bae3c21
Author:     Sukadev Bhattiprolu <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 18 23:39:49 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Oct 19 11:53:37 2007 -0700

    pid namespaces: define and use task_active_pid_ns() wrapper
    With multiple pid namespaces, a process is known by some pid_t in every
    ancestor pid namespace.  Every time the process forks, the child process 
    gets a pid_t in every ancestor pid namespace.
    While a process is visible in >=1 pid namespaces, it can see pid_t's in only
    one pid namespace.  We call this pid namespace it's "active pid namespace",
    and it is always the youngest pid namespace in which the process is known.
    This patch defines and uses a wrapper to find the active pid namespace of a
    process.  The implementation of the wrapper will be changed in when support
    for multiple pid namespaces are added.
        - [Pavel Emelianov, Alexey Dobriyan] Back out the change to use
          task_active_pid_ns() in child_reaper() since task->nsproxy
          can be NULL during task exit (so child_reaper() continues to
          use init_pid_ns).
          to implement child_reaper() since init_pid_ns.child_reaper to
          implement child_reaper() since tsk->nsproxy can be NULL during exit.
        - Rename task_pid_ns() to task_active_pid_ns() to reflect that a
          process can have multiple pid namespaces.
    Signed-off-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
    Acked-by: Pavel Emelianov <[EMAIL PROTECTED]>
    Cc: Eric W. Biederman <[EMAIL PROTECTED]>
    Cc: Cedric Le Goater <[EMAIL PROTECTED]>
    Cc: Dave Hansen <[EMAIL PROTECTED]>
    Cc: Serge Hallyn <[EMAIL PROTECTED]>
    Cc: Herbert Poetzel <[EMAIL PROTECTED]>
    Cc: Kirill Korotaev <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 fs/exec.c                     |    2 +-
 fs/proc/proc_misc.c           |    3 ++-
 include/linux/pid_namespace.h |    5 +++++
 kernel/nsproxy.c              |    2 +-
 kernel/pid.c                  |    4 ++--
 5 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 0b09447..6ffb769 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -776,7 +776,7 @@ static int de_thread(struct task_struct *tsk)
         * so it is safe to do it under read_lock.
        if (unlikely(tsk->group_leader == child_reaper(tsk)))
-               tsk->nsproxy->pid_ns->child_reaper = tsk;
+               task_active_pid_ns(tsk)->child_reaper = tsk;
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index d6dc72c..e0d064e 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -91,7 +91,8 @@ static int loadavg_read_proc(char *page, char **start, off_t 
                LOAD_INT(a), LOAD_FRAC(a),
                LOAD_INT(b), LOAD_FRAC(b),
                LOAD_INT(c), LOAD_FRAC(c),
-               nr_running(), nr_threads, current->nsproxy->pid_ns->last_pid);
+               nr_running(), nr_threads,
+               task_active_pid_ns(current)->last_pid);
        return proc_calc_metrics(page, start, off, count, eof, len);
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index c471c0c..d10cb5f 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -39,6 +39,11 @@ static inline void put_pid_ns(struct pid_namespace *ns)
        kref_put(&ns->kref, free_pid_ns);
+static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
+       return tsk->nsproxy->pid_ns;
 static inline struct task_struct *child_reaper(struct task_struct *tsk)
        return init_pid_ns.child_reaper;
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index ac99837..e981c61 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -87,7 +87,7 @@ static struct nsproxy *create_new_namespaces(unsigned long 
                goto out_ipc;
-       new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
+       new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
        if (IS_ERR(new_nsp->pid_ns)) {
                err = PTR_ERR(new_nsp->pid_ns);
                goto out_pid;
diff --git a/kernel/pid.c b/kernel/pid.c
index 42de9af..78c0dbf 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -214,7 +214,7 @@ struct pid *alloc_pid(void)
        int nr = -1;
        struct pid_namespace *ns;
-       ns = current->nsproxy->pid_ns;
+       ns = task_active_pid_ns(current);
        pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
        if (!pid)
                goto out;
@@ -364,7 +364,7 @@ struct pid *find_ge_pid(int nr)
                pid = find_pid(nr);
                if (pid)
-               nr = next_pidmap(current->nsproxy->pid_ns, nr);
+               nr = next_pidmap(task_active_pid_ns(current), nr);
        } while (nr > 0);
        return pid;
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