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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>
This commit is contained in:
KAMEZAWA Hiroyuki 2011-03-23 16:42:18 -07:00 committed by Linus Torvalds
parent 61f2e7b0f4
commit 6c191cd01a
1 changed files with 14 additions and 0 deletions
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14
kernel/res_counter.c
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@ -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)