From 6c191cd01a935e5b53ef43c9403c771bb7a32b60 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Date: Wed, 23 Mar 2011 16:42:18 -0700 Subject: [PATCH] memcg: res_counter_read_u64(): fix potential races on 32-bit machines res_counter_read_u64 reads u64 value without lock. It's dangerous in a 32bit environment. Add locking. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- kernel/res_counter.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/kernel/res_counter.c b/kernel/res_counter.c index c7eaa37a768b..34683efa2cce 100644 --- a/kernel/res_counter.c +++ b/kernel/res_counter.c @@ -126,10 +126,24 @@ ssize_t res_counter_read(struct res_counter *counter, int member, pos, buf, s - buf); } +#if BITS_PER_LONG == 32 +u64 res_counter_read_u64(struct res_counter *counter, int member) +{ + unsigned long flags; + u64 ret; + + spin_lock_irqsave(&counter->lock, flags); + ret = *res_counter_member(counter, member); + spin_unlock_irqrestore(&counter->lock, flags); + + return ret; +} +#else u64 res_counter_read_u64(struct res_counter *counter, int member) { return *res_counter_member(counter, member); } +#endif int res_counter_memparse_write_strategy(const char *buf, unsigned long long *res) -- GitLab