BKL: Remove BKL from cgroup

The BKL is only used in remount_fs and get_sb that are both protected by
the superblocks s_umount rw_semaphore. Therefore it is safe to remove the
BKL entirely.
Signed-off-by: Jan Blunck <jblunck@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

kernel/cgroup.c

@@ -52,7 +52,6 @@
 #include <linux/cgroupstats.h>
 #include <linux/hash.h>
 #include <linux/namei.h>
-#include <linux/smp_lock.h>
 #include <linux/pid_namespace.h>
 #include <linux/idr.h>
 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
@@ -1222,7 +1221,6 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
 	struct cgroup *cgrp = &root->top_cgroup;
 	struct cgroup_sb_opts opts;
 
-	lock_kernel();
 	mutex_lock(&cgrp->dentry->d_inode->i_mutex);
 	mutex_lock(&cgroup_mutex);
 
@@ -1255,7 +1253,6 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
 	kfree(opts.name);
 	mutex_unlock(&cgroup_mutex);
 	mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
-	unlock_kernel();
 	return ret;
 }
 
@@ -1430,8 +1427,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 	struct super_block *sb;
 	struct cgroupfs_root *new_root;
 
-	lock_kernel();
-
 	/* First find the desired set of subsystems */
 	mutex_lock(&cgroup_mutex);
 	ret = parse_cgroupfs_options(data, &opts);
@@ -1561,7 +1556,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
 	simple_set_mnt(mnt, sb);
 	kfree(opts.release_agent);
 	kfree(opts.name);
-	unlock_kernel();
 	return 0;
 
  drop_new_super:
@@ -1571,8 +1565,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
  out_err:
 	kfree(opts.release_agent);
 	kfree(opts.name);
-	unlock_kernel();
-
 	return ret;
 }