umh: creds: kill subprocess_info->cred logic

Now that nobody ever changes subprocess_info->cred we can kill this member
and related code.  ____call_usermodehelper() always runs in the context of
freshly forked kernel thread, it has the proper ->cred copied from its
parent kthread, keventd.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 19 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 743d3883517c..6194ec2f737b 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -134,8 +134,6 @@ static int ____call_usermodehelper(void *data)
         struct subprocess_info *sub_info = data;
         int retval;
 
-        BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
         /* Unblock all signals */
         spin_lock_irq(&current->sighand->siglock);
         flush_signal_handlers(current, 1);
@@ -143,10 +141,6 @@ static int ____call_usermodehelper(void *data)
         recalc_sigpending();
         spin_unlock_irq(&current->sighand->siglock);
 
-        /* Install the credentials */
-        commit_creds(sub_info->cred);
-        sub_info->cred = NULL;
-
         /* We can run anywhere, unlike our parent keventd(). */
         set_cpus_allowed_ptr(current, cpu_all_mask);
 
@@ -174,8 +168,6 @@ void call_usermodehelper_freeinfo(struct subprocess_info *info)
 {
         if (info->cleanup)
                 (*info->cleanup)(info);
-        if (info->cred)
-                put_cred(info->cred);
         kfree(info);
 }
 EXPORT_SYMBOL(call_usermodehelper_freeinfo);
@@ -231,8 +223,6 @@ static void __call_usermodehelper(struct work_struct *work)
         pid_t pid;
         enum umh_wait wait = sub_info->wait;
 
-        BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-
         /* CLONE_VFORK: wait until the usermode helper has execve'd
          * successfully We need the data structures to stay around
          * until that is done.  */
@@ -355,12 +345,6 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
         sub_info->path = path;
         sub_info->argv = argv;
         sub_info->envp = envp;
-        sub_info->cred = prepare_usermodehelper_creds();
-        if (!sub_info->cred) {
-                kfree(sub_info);
-                return NULL;
-        }
-
   out:
         return sub_info;
 }
@@ -411,9 +395,6 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
         DECLARE_COMPLETION_ONSTACK(done);
         int retval = 0;
 
-        BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
-        validate_creds(sub_info->cred);
-
         helper_lock();
         if (sub_info->path[0] == '\0')
                 goto out;