swap_cgroup uses 2bytes data and uses cmpxchg in a new operation. 2byte
cmpxchg/xchg is not available on some archs. This patch replaces
cmpxchg/xchg with operations under lock.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reported-by: Sachin Sant <sachinp@in.ibm.com> wrote:
Acked-by: Balbir Singh <balbir@in.ibm.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct swap_cgroup_ctrl {
struct page **map;
unsigned long length;
struct swap_cgroup_ctrl {
struct page **map;
unsigned long length;
};
struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
};
struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
struct swap_cgroup_ctrl *ctrl;
struct page *mappage;
struct swap_cgroup *sc;
struct swap_cgroup_ctrl *ctrl;
struct page *mappage;
struct swap_cgroup *sc;
+ unsigned long flags;
+ unsigned short retval;
ctrl = &swap_cgroup_ctrl[type];
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
ctrl = &swap_cgroup_ctrl[type];
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
- if (cmpxchg(&sc->id, old, new) == old)
- return old;
+ spin_lock_irqsave(&ctrl->lock, flags);
+ retval = sc->id;
+ if (retval == old)
+ sc->id = new;
+ retval = 0;
+ spin_unlock_irqrestore(&ctrl->lock, flags);
+ return retval;
struct page *mappage;
struct swap_cgroup *sc;
unsigned short old;
struct page *mappage;
struct swap_cgroup *sc;
unsigned short old;
ctrl = &swap_cgroup_ctrl[type];
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
ctrl = &swap_cgroup_ctrl[type];
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
- old = xchg(&sc->id, id);
+ spin_lock_irqsave(&ctrl->lock, flags);
+ old = sc->id;
+ sc->id = id;
+ spin_unlock_irqrestore(&ctrl->lock, flags);
mutex_lock(&swap_cgroup_mutex);
ctrl->length = length;
ctrl->map = array;
mutex_lock(&swap_cgroup_mutex);
ctrl->length = length;
ctrl->map = array;
+ spin_lock_init(&ctrl->lock);
if (swap_cgroup_prepare(type)) {
/* memory shortage */
ctrl->map = NULL;
if (swap_cgroup_prepare(type)) {
/* memory shortage */
ctrl->map = NULL;