Messages in this thread | | | Date | Thu, 15 Mar 2012 13:01:00 -0400 | From | Vivek Goyal <> | Subject | Re: [PATCH block/for-3.4/core] cfq: fix cfqg ref handling when BLK_CGROUP && !CFQ_GROUP_IOSCHED |
| |
On Thu, Mar 15, 2012 at 09:50:57AM -0700, Tejun Heo wrote:
> > [..] > > > @@ -3533,7 +3551,7 @@ static int cfq_init_queue(struct request > > > > > > spin_lock_irq(q->queue_lock); > > > cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group); > > > - blkg_put(cfqg_to_blkg(cfqd->root_group)); > > > + cfqg_put(cfqd->root_group); > > > > This seems to be a spurious cfqg_put()? Which reference we are putting > > down here? > > The extra ref from cfq_link_cfqq_cfqg() for oom_cfqq; otherwise, we > need an extra cfq_put() in cfq_exit_queue(). I thought I wrote > comment about that somewhere. Hmmm.... apparently not. The thing is > that oom_cfqq doesn't go through proper cfqq destruction and thus > never puts the extra ref to root cfqg.
Ok. Is cfq_exit_queue() a better place to put down this reference explicitly with a comment. Even if you keep it here, atleast a comment is required. It is not obvious at all (atleast to me).
Thanks Vivek
| |