[Devel] [RFC][PATCH] Define/use task_pid_ns() wrapper

[sukadev at us.ibm.com]

From: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Subject: [RFC][PATCH] Define/use task_pid_ns() wrapper

Use a wrapper to access/set pid_namespace of a task.

Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Cc: Cedric Le Goater <clg at fr.ibm.com>
Cc: Dave Hansen <haveblue at us.ibm.com>
Cc: Serge Hallyn <serue at us.ibm.com>
Cc: containers at lists.osdl.org

---
 fs/exec.c                     |    2 +-
 fs/proc/proc_misc.c           |    2 +-
 include/linux/pid_namespace.h |   11 +++++++++++
 kernel/exit.c                 |    4 ++--
 kernel/pid.c                  |    6 +++---
 5 files changed, 18 insertions(+), 7 deletions(-)

Index: lx26-20-mm2b/fs/exec.c
===================================================================
--- lx26-20-mm2b.orig/fs/exec.c	2007-03-01 15:19:15.000000000 -0800
+++ lx26-20-mm2b/fs/exec.c	2007-03-01 15:20:52.000000000 -0800
@@ -620,7 +620,7 @@ static int de_thread(struct task_struct 
 	 * 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_pid_ns(tsk)->child_reaper = tsk;
 
 	zap_other_threads(tsk);
 	read_unlock(&tasklist_lock);
Index: lx26-20-mm2b/fs/proc/proc_misc.c
===================================================================
--- lx26-20-mm2b.orig/fs/proc/proc_misc.c	2007-03-01 15:19:15.000000000 -0800
+++ lx26-20-mm2b/fs/proc/proc_misc.c	2007-03-01 15:20:52.000000000 -0800
@@ -93,7 +93,7 @@ static int loadavg_read_proc(char *page,
 		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_pid_ns(current)->last_pid);
 	return proc_calc_metrics(page, start, off, count, eof, len);
 }
 
Index: lx26-20-mm2b/kernel/exit.c
===================================================================
--- lx26-20-mm2b.orig/kernel/exit.c	2007-03-01 15:19:15.000000000 -0800
+++ lx26-20-mm2b/kernel/exit.c	2007-03-01 15:20:52.000000000 -0800
@@ -790,8 +790,8 @@ fastcall NORET_TYPE void do_exit(long co
 	if (unlikely(!tsk->pid))
 		panic("Attempted to kill the idle task!");
 	if (unlikely(tsk == child_reaper(tsk))) {
-		if (tsk->nsproxy->pid_ns != &init_pid_ns)
-			tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
+		if (task_pid_ns(tsk) != &init_pid_ns)
+			task_pid_ns(tsk)->child_reaper = init_pid_ns.child_reaper;
 		else
 			panic("Attempted to kill init!");
 	}
Index: lx26-20-mm2b/kernel/pid.c
===================================================================
--- lx26-20-mm2b.orig/kernel/pid.c	2007-03-01 15:19:15.000000000 -0800
+++ lx26-20-mm2b/kernel/pid.c	2007-03-07 19:52:21.000000000 -0800
@@ -213,7 +213,7 @@ struct pid *alloc_pid(void)
 	if (!pid)
 		goto out;
 
-	nr = alloc_pidmap(current->nsproxy->pid_ns);
+	nr = alloc_pidmap(task_pid_ns(current));
 	if (nr < 0)
 		goto out_free;
 
@@ -358,7 +358,7 @@ struct pid *find_ge_pid(int nr)
 		pid = find_pid(nr);
 		if (pid)
 			break;
-		nr = next_pidmap(current->nsproxy->pid_ns, nr);
+		nr = next_pidmap(task_pid_ns(current), nr);
 	} while (nr > 0);
 
 	return pid;
@@ -367,7 +367,7 @@ EXPORT_SYMBOL_GPL(find_get_pid);
 
 int copy_pid_ns(int flags, struct task_struct *tsk)
 {
-	struct pid_namespace *old_ns = tsk->nsproxy->pid_ns;
+	struct pid_namespace *old_ns = task_pid_ns(tsk);
 	int err = 0;
 
 	if (!old_ns)
Index: lx26-20-mm2b/include/linux/pid_namespace.h
===================================================================
--- lx26-20-mm2b.orig/include/linux/pid_namespace.h	2007-03-01 15:19:15.000000000 -0800
+++ lx26-20-mm2b/include/linux/pid_namespace.h	2007-03-07 19:52:21.000000000 -0800
@@ -37,6 +37,17 @@ static inline void put_pid_ns(struct pid
 	kref_put(&ns->kref, free_pid_ns);
 }
 
+static inline struct pid_namespace *task_pid_ns(struct task_struct *tsk)
+{
+        return tsk->nsproxy->pid_ns;
+}
+
+static inline void set_task_pid_ns(struct task_struct *tsk,
+				struct pid_namespace * ns)
+{
+        tsk->nsproxy->pid_ns = ns
+}
+
 static inline struct task_struct *child_reaper(struct task_struct *tsk)
 {
 	return init_pid_ns.child_reaper;
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