Re: [PATCH 7/7] memcg : remove ugly vairable initialization by callers

[Johannes Weiner <hannes@cmpxchg.org>]

On Fri, Jan 21, 2011 at 03:50:51PM +0900, KAMEZAWA Hiroyuki wrote:
> This is a promised one.
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> This patch is for removing initialization in caller of memory cgroup
> function. Some memory cgroup uses following style to bring the result
> of start function to the end function for avoiding races.
> 
>    mem_cgroup_start_A(&(*ptr))
>    /* Something very complicated can happen here. */
>    mem_cgroup_end_A(*ptr)
> 
> In some calls, *ptr should be initialized to NULL be caller. But
> it's ugly. This patch fixes that *ptr is initialized by _start
> function.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Nitpick: I would remove the comments above the *ptr = NULL lines,
there should be no assumptions about the consequences in the caller
(the next patch will change the caller, and then the comments are
nothing but confusing).  It's just a plain initialization of a return
value.