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authorKirill Tkhai <ktkhai@virtuozzo.com>2020-08-03 13:16:32 +0300
committerChristian Brauner <christian.brauner@ubuntu.com>2020-08-19 14:14:06 +0200
commit8eb71d95f34a009cc22084e05e78eb9686f7ea28 (patch)
treedf4935999b148f4b5aae6d97688409a7c986c105 /kernel/pid_namespace.c
parent137ec390fad41928307216ea9f91acf5cf6f4204 (diff)
pid: Use generic ns_common::count
Switch over pid namespaces to use the newly introduced common lifetime counter. Currently every namespace type has its own lifetime counter which is stored in the specific namespace struct. The lifetime counters are used identically for all namespaces types. Namespaces may of course have additional unrelated counters and these are not altered. This introduces a common lifetime counter into struct ns_common. The ns_common struct encompasses information that all namespaces share. That should include the lifetime counter since its common for all of them. It also allows us to unify the type of the counters across all namespaces. Most of them use refcount_t but one uses atomic_t and at least one uses kref. Especially the last one doesn't make much sense since it's just a wrapper around refcount_t since 2016 and actually complicates cleanup operations by having to use container_of() to cast the correct namespace struct out of struct ns_common. Having the lifetime counter for the namespaces in one place reduces maintenance cost. Not just because after switching all namespaces over we will have removed more code than we added but also because the logic is more easily understandable and we indicate to the user that the basic lifetime requirements for all namespaces are currently identical. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/159644979226.604812.7512601754841882036.stgit@localhost.localdomain Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Diffstat (limited to 'kernel/pid_namespace.c')
-rw-r--r--kernel/pid_namespace.c13
1 files changed, 3 insertions, 10 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index ac135bd600eb..166a91cdd387 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -102,7 +102,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
goto out_free_idr;
ns->ns.ops = &pidns_operations;
- kref_init(&ns->kref);
+ refcount_set(&ns->ns.count, 1);
ns->level = level;
ns->parent = get_pid_ns(parent_pid_ns);
ns->user_ns = get_user_ns(user_ns);
@@ -148,22 +148,15 @@ struct pid_namespace *copy_pid_ns(unsigned long flags,
return create_pid_namespace(user_ns, old_ns);
}
-static void free_pid_ns(struct kref *kref)
-{
- struct pid_namespace *ns;
-
- ns = container_of(kref, struct pid_namespace, kref);
- destroy_pid_namespace(ns);
-}
-
void put_pid_ns(struct pid_namespace *ns)
{
struct pid_namespace *parent;
while (ns != &init_pid_ns) {
parent = ns->parent;
- if (!kref_put(&ns->kref, free_pid_ns))
+ if (!refcount_dec_and_test(&ns->ns.count))
break;
+ destroy_pid_namespace(ns);
ns = parent;
}
}

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