Revert "[PATCH] namespaces: fix exit race by splitting exit"

This reverts commit 7a238fcba0629b6f2edbcd37458bae56fcf36be5 in
preparation for a better and simpler fix proposed by Eric Biederman
(and fixed up by Serge Hallyn)

Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 16 insertions, 40 deletions

diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 678e1d38effb..0b9f0dc30d61 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -35,30 +35,22 @@ 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 free_nsproxy(struct nsproxy *ns);
-struct nsproxy *put_nsproxy(struct nsproxy *ns);
 
-static inline void finalize_put_nsproxy(struct nsproxy *ns)
+static inline void put_nsproxy(struct nsproxy *ns)
 {
-        if (ns)
+        if (atomic_dec_and_test(&ns->count)) {
                 free_nsproxy(ns);
+        }
 }
 
-static inline void put_and_finalize_nsproxy(struct nsproxy *ns)
+static inline void exit_task_namespaces(struct task_struct *p)
 {
-        finalize_put_nsproxy(put_nsproxy(ns));
-}
-
-static inline struct nsproxy *preexit_task_namespaces(struct task_struct *p)
-{
-        return put_nsproxy(p->nsproxy);
-}
-
-static inline void exit_task_namespaces(struct task_struct *p,
-                                                struct nsproxy *ns)
-{
-        task_lock(p);
-        p->nsproxy = NULL;
-        task_unlock(p);
-        finalize_put_nsproxy(ns);
+        struct nsproxy *ns = p->nsproxy;
+        if (ns) {
+                task_lock(p);
+                p->nsproxy = NULL;
+                task_unlock(p);
+                put_nsproxy(ns);
+        }
 }
 #endif
diff --git a/kernel/exit.c b/kernel/exit.c
index a5bf5329ff97..35401720635b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -396,7 +396,7 @@ void daemonize(const char *name, ...)
         current->fs = fs;
         atomic_inc(&fs->count);
 
-        put_and_finalize_nsproxy(current->nsproxy);
+        exit_task_namespaces(current);
         current->nsproxy = init_task.nsproxy;
         get_task_namespaces(current);
 
@@ -853,7 +853,6 @@ static void exit_notify(struct task_struct *tsk)
 fastcall NORET_TYPE void do_exit(long code)
 {
         struct task_struct *tsk = current;
-        struct nsproxy *ns;
         int group_dead;
 
         profile_task_exit(tsk);
@@ -939,9 +938,8 @@ fastcall NORET_TYPE void do_exit(long code)
 
         tsk->exit_code = code;
         proc_exit_connector(tsk);
-        ns = preexit_task_namespaces(tsk);
         exit_notify(tsk);
-        exit_task_namespaces(tsk, ns);
+        exit_task_namespaces(tsk);
 #ifdef CONFIG_NUMA
         mpol_free(tsk->mempolicy);
         tsk->mempolicy = NULL;
diff --git a/kernel/fork.c b/kernel/fork.c
index 4cf868458f06..fc723e595cd5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1265,7 +1265,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         return p;
 
 bad_fork_cleanup_namespaces:
-        put_and_finalize_nsproxy(p->nsproxy);
+        exit_task_namespaces(p);
 bad_fork_cleanup_keys:
         exit_keys(p);
 bad_fork_cleanup_mm:
@@ -1711,7 +1711,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
         }
 
         if (new_nsproxy)
-                put_and_finalize_nsproxy(new_nsproxy);
+                put_nsproxy(new_nsproxy);
 
 bad_unshare_cleanup_ipc:
         if (new_ipc)
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 7b05bce75cde..f5b9ee6f6bbb 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -117,7 +117,7 @@ int copy_namespaces(int flags, struct task_struct *tsk)
                 goto out_pid;
 
 out:
-        put_and_finalize_nsproxy(old_ns);
+        put_nsproxy(old_ns);
         return err;
 
 out_pid:
@@ -135,20 +135,6 @@ out_ns:
         goto out;
 }
 
-struct nsproxy *put_nsproxy(struct nsproxy *ns)
-{
-        if (ns) {
-                if (atomic_dec_and_test(&ns->count)) {
-                        if (ns->mnt_ns) {
-                                put_mnt_ns(ns->mnt_ns);
-                                ns->mnt_ns = NULL;
-                        }
-                        return ns;
-                }
-        }
-        return NULL;
-}
-
 void free_nsproxy(struct nsproxy *ns)
 {
         if (ns->mnt_ns)