Quoting Eric W. Biederman ([email protected]):
> "Serge E. Hallyn" <[email protected]> writes:
>
>
> > @@ -1727,11 +1727,16 @@ static void __init init_mount_tree(void)
> > namespace->root = mnt;
> > mnt->mnt_namespace = namespace;
> >
> > - init_task.namespace = namespace;
> > + init_task.nsproxy->namespace = namespace;
> > read_lock(&tasklist_lock);
> > do_each_thread(g, p) {
> > + /* do we want namespace count to be #nsproxies,
> > + * or # processes pointing to the namespace? */
>
> I am fairly certain we want the count to be #nsproxies.
>
> > get_namespace(namespace);
> > - p->namespace = namespace;
> > +#if 0
> > + /* should only be 1 nsproxy so far */
> > + p->nsproxy->namespace = namespace;
> > +#endif
> > } while_each_thread(g, p);
> > read_unlock(&tasklist_lock);
>
> So I think this bit is wrong.
Here is a patch (on top of the patchset + the patch I sent in response
to Dave) to change the fs namespace and utsname ->counts to being the
number of nsproxies holding a reference.
thanks,
-serge
Subject: [PATCH 11/11] nsproxy: change meaning of namespace refcount
switch namespace+utsname refcount to count nsproxies
Signed-off-by: <[email protected]>
---
fs/namespace.c | 13 +------------
include/linux/nsproxy.h | 18 +++++++++---------
kernel/fork.c | 3 +--
kernel/nsproxy.c | 39 ++++++++++++++-------------------------
4 files changed, 25 insertions(+), 48 deletions(-)
41b3b9a9df03156627adc34b88c041dd3ade1236
diff --git a/fs/namespace.c b/fs/namespace.c
index 851a02d..33330fe 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1711,7 +1711,6 @@ static void __init init_mount_tree(void)
{
struct vfsmount *mnt;
struct namespace *namespace;
- struct task_struct *g, *p;
mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
if (IS_ERR(mnt))
@@ -1728,17 +1727,7 @@ static void __init init_mount_tree(void)
mnt->mnt_namespace = namespace;
init_task.nsproxy->namespace = namespace;
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- /* do we want namespace count to be #nsproxies,
- * or # processes pointing to the namespace? */
- get_namespace(namespace);
-#if 0
- /* should only be 1 nsproxy so far */
- p->nsproxy->namespace = namespace;
-#endif
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
+ get_namespace(namespace);
set_fs_pwd(current->fs, namespace->root, namespace->root->mnt_root);
set_fs_root(current->fs, namespace->root, namespace->root->mnt_root);
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 6046fc3..3793017 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -17,21 +17,21 @@ extern struct nsproxy init_nsproxy;
struct nsproxy *dup_namespaces(struct nsproxy *orig);
int copy_namespaces(int flags, struct task_struct *tsk);
void get_task_namespaces(struct task_struct *tsk);
-void exit_namespaces(struct nsproxy *ns);
+void free_nsproxy(struct nsproxy *ns);
-static inline void exit_task_namespaces(struct task_struct *p)
+static inline void put_nsproxy(struct nsproxy *ns)
{
- struct nsproxy *ns = p->nsproxy;
- if (ns) {
- exit_namespaces(p->nsproxy);
- p->nsproxy = NULL;
+ if (atomic_dec_and_test(&ns->count)) {
+ free_nsproxy(ns);
}
}
-static inline void put_nsproxy(struct nsproxy *nsp)
+static inline void exit_task_namespaces(struct task_struct *p)
{
- if (atomic_dec_and_test(&nsp->count)) {
- kfree(nsp);
+ struct nsproxy *ns = p->nsproxy;
+ if (ns) {
+ put_nsproxy(ns);
+ p->nsproxy = NULL;
}
}
#endif
diff --git a/kernel/fork.c b/kernel/fork.c
index f9b607c..6214427 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1470,8 +1470,7 @@ static int unshare_namespace(unsigned lo
{
struct namespace *ns = current->nsproxy->namespace;
- if ((unshare_flags & CLONE_NEWNS) &&
- (ns && atomic_read(&ns->count) > 1)) {
+ if ((unshare_flags & CLONE_NEWNS) && ns) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index d963af9..19abf95 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -21,26 +21,18 @@ static inline void get_nsproxy(struct ns
atomic_inc(&ns->count);
}
-static inline void get_namespaces(struct nsproxy *ns)
-{
- get_nsproxy(ns);
- if (ns->namespace)
- get_namespace(ns->namespace);
- if (ns->uts_ns)
- get_uts_ns(ns->uts_ns);
-}
-
void get_task_namespaces(struct task_struct *tsk)
{
struct nsproxy *ns = tsk->nsproxy;
if (ns) {
- get_namespaces(ns);
+ get_nsproxy(ns);
}
}
/*
* creates a copy of "orig" with refcount 1.
- * This does not grab references to the contained namespaces.
+ * This does not grab references to the contained namespaces,
+ * so that needs to be done by dup_namespaces.
*/
static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
{
@@ -74,18 +66,6 @@ struct nsproxy *dup_namespaces(struct ns
}
/*
- * Put refcount on nsproxy and each namespace therein
- */
-void exit_namespaces(struct nsproxy *ns)
-{
- if (ns->namespace)
- put_namespace(ns->namespace);
- if (ns->uts_ns)
- put_uts_ns(ns->uts_ns);
- put_nsproxy(ns);
-}
-
-/*
* called from clone. This now handles copy for nsproxy and all
* namespaces therein.
*/
@@ -98,7 +78,7 @@ int copy_namespaces(int flags, struct ta
if (!old_ns)
return 0;
- get_namespaces(old_ns);
+ get_nsproxy(old_ns);
if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS)))
return 0;
@@ -128,6 +108,15 @@ int copy_namespaces(int flags, struct ta
}
out:
- exit_namespaces(old_ns);
+ put_nsproxy(old_ns);
return err;
}
+
+void free_nsproxy(struct nsproxy *ns)
+{
+ if (ns->namespace)
+ put_namespace(ns->namespace);
+ if (ns->uts_ns)
+ put_uts_ns(ns->uts_ns);
+ kfree(ns);
+}
--
1.1.6
-
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