A separate patch to simplify the review of the next change.
Move destroy_pid_namespace() into workqueue context. This allows us to do
mntput() from free_pid_ns() paths, see the next patch.
Add the new member, "struct work_struct destroy" into struct pid_namespace
and change free_pid_ns() to call destroy_pid_namespace() via schedule_work().
The patch looks a bit complicated because it also moves copy_pid_ns() up.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/pid_namespace.h | 1 +
kernel/pid_namespace.c | 25 +++++++++++++++++--------
2 files changed, 18 insertions(+), 8 deletions(-)
--- 35-rc3/include/linux/pid_namespace.h~PNS_5_DESTROY_FROM_WQ 2009-04-06 00:03:41.000000000 +0200
+++ 35-rc3/include/linux/pid_namespace.h 2010-06-20 17:47:05.000000000 +0200
@@ -24,6 +24,7 @@ struct pid_namespace {
struct kmem_cache *pid_cachep;
unsigned int level;
struct pid_namespace *parent;
+ struct work_struct destroy;
#ifdef CONFIG_PROC_FS
struct vfsmount *proc_mnt;
#endif
--- 35-rc3/kernel/pid_namespace.c~PNS_5_DESTROY_FROM_WQ 2010-06-19 19:21:42.000000000 +0200
+++ 35-rc3/kernel/pid_namespace.c 2010-06-20 18:36:00.000000000 +0200
@@ -114,6 +114,16 @@ out:
return ERR_PTR(err);
}
+struct pid_namespace *copy_pid_ns(unsigned long flags,
+ struct pid_namespace *old_ns)
+{
+ if (!(flags & CLONE_NEWPID))
+ return get_pid_ns(old_ns);
+ if (flags & (CLONE_THREAD|CLONE_PARENT))
+ return ERR_PTR(-EINVAL);
+ return create_pid_namespace(old_ns);
+}
+
static void destroy_pid_namespace(struct pid_namespace *ns)
{
int i;
@@ -123,13 +133,11 @@ static void destroy_pid_namespace(struct
kmem_cache_free(pid_ns_cachep, ns);
}
-struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
+static void destroy_pid_namespace_work(struct work_struct *work)
{
- if (!(flags & CLONE_NEWPID))
- return get_pid_ns(old_ns);
- if (flags & (CLONE_THREAD|CLONE_PARENT))
- return ERR_PTR(-EINVAL);
- return create_pid_namespace(old_ns);
+ struct pid_namespace *ns =
+ container_of(work, struct pid_namespace, destroy);
+ destroy_pid_namespace(ns);
}
void free_pid_ns(struct kref *kref)
@@ -137,9 +145,10 @@ void free_pid_ns(struct kref *kref)
struct pid_namespace *ns, *parent;
ns = container_of(kref, struct pid_namespace, kref);
-
parent = ns->parent;
- destroy_pid_namespace(ns);
+
+ INIT_WORK(&ns->destroy, destroy_pid_namespace_work);
+ schedule_work(&ns->destroy);
if (parent != NULL)
put_pid_ns(parent);
--
