cgroup: don't online subsystems before cgroup_name/path() are operational

While refactoring cgroup creation, a5bca2152036 ("cgroup: factor out
cgroup_create() out of cgroup_mkdir()") incorrectly onlined subsystems
before the new cgroup is associated with it kernfs_node.  This is fine
for cgroup proper but cgroup_name/path() depend on the associated
kernfs_node and if a subsystem makes the new cgroup_subsys_state
visible, which they're allowed to after onlining, it can lead to NULL
dereference.

The current code performs cgroup creation and subsystem onlining in
cgroup_create() and cgroup_mkdir() makes the cgroup and subsystems
visible afterwards.  There's no reason to online the subsystems early
and we can simply drop cgroup_apply_control_enable() call from
cgroup_create() so that the subsystems are onlined and made visible at
the same time.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: a5bca2152036 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()") 
Cc: stable@vger.kernel.org # v4.6+

path: root/tools/perf/arch/xtensa/util/dwarf-regs.c

/*
 * Mapping of DWARF debug register numbers into register names.
 *
 * Copyright (c) 2015 Cadence Design Systems Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <stddef.h>
#include <dwarf-regs.h>

#define XTENSA_MAX_REGS 16

const char *xtensa_regs_table[XTENSA_MAX_REGS] = {
	"a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
	"a8", "a9", "a10", "a11", "a12", "a13", "a14", "a15",
};

const char *get_arch_regstr(unsigned int n)
{
	return n < XTENSA_MAX_REGS ? xtensa_regs_table[n] : NULL;
}