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Subject: [PATCH 02/23] uts: Use generic ns_common::count
From:   Kirill Tkhai <ktkhai@virtuozzo.com>
To:     viro@zeniv.linux.org.uk, adobriyan@gmail.com, davem@davemloft.net,
        ebiederm@xmission.com, akpm@linux-foundation.org,
        christian.brauner@ubuntu.com, areber@redhat.com, serge@hallyn.com,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        ktkhai@virtuozzo.com
Date:   Thu, 30 Jul 2020 14:59:31 +0300
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Convert uts namespace to use generic counter instead of kref.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 include/linux/utsname.h |    9 ++++-----
 init/version.c          |    2 +-
 kernel/utsname.c        |    7 ++-----
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 44429d9142ca..2b1737c9b244 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -4,7 +4,6 @@
 
 
 #include <linux/sched.h>
-#include <linux/kref.h>
 #include <linux/nsproxy.h>
 #include <linux/ns_common.h>
 #include <linux/err.h>
@@ -22,7 +21,6 @@ struct user_namespace;
 extern struct user_namespace init_user_ns;
 
 struct uts_namespace {
-	struct kref kref;
 	struct new_utsname name;
 	struct user_namespace *user_ns;
 	struct ucounts *ucounts;
@@ -33,16 +31,17 @@ extern struct uts_namespace init_uts_ns;
 #ifdef CONFIG_UTS_NS
 static inline void get_uts_ns(struct uts_namespace *ns)
 {
-	kref_get(&ns->kref);
+	refcount_inc(&ns->ns.count);
 }
 
 extern struct uts_namespace *copy_utsname(unsigned long flags,
 	struct user_namespace *user_ns, struct uts_namespace *old_ns);
-extern void free_uts_ns(struct kref *kref);
+extern void free_uts_ns(struct uts_namespace *ns);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
 {
-	kref_put(&ns->kref, free_uts_ns);
+	if (refcount_dec_and_test(&ns->ns.count))
+		free_uts_ns(ns);
 }
 
 void uts_ns_init(void);
diff --git a/init/version.c b/init/version.c
index cba341161b58..80d2b7566b39 100644
--- a/init/version.c
+++ b/init/version.c
@@ -25,7 +25,7 @@ int version_string(LINUX_VERSION_CODE);
 #endif
 
 struct uts_namespace init_uts_ns = {
-	.kref = KREF_INIT(2),
+	.ns.count = REFCOUNT_INIT(2),
 	.name = {
 		.sysname	= UTS_SYSNAME,
 		.nodename	= UTS_NODENAME,
diff --git a/kernel/utsname.c b/kernel/utsname.c
index e488d0e2ab45..b1ac3ca870f2 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -33,7 +33,7 @@ static struct uts_namespace *create_uts_ns(void)
 
 	uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
 	if (uts_ns)
-		kref_init(&uts_ns->kref);
+		refcount_set(&uts_ns->ns.count, 1);
 	return uts_ns;
 }
 
@@ -103,11 +103,8 @@ struct uts_namespace *copy_utsname(unsigned long flags,
 	return new_ns;
 }
 
-void free_uts_ns(struct kref *kref)
+void free_uts_ns(struct uts_namespace *ns)
 {
-	struct uts_namespace *ns;
-
-	ns = container_of(kref, struct uts_namespace, kref);
 	dec_uts_namespaces(ns->ucounts);
 	put_user_ns(ns->user_ns);
 	ns_free_inum(&ns->ns);