Re: [PATCH 01/11] blkcg: fix blkg_alloc() failure path

Tejun Heo
2012-04-27T14:28:05Z

On Fri, Apr 27, 2012 at 10:26:52AM -0400, Vivek Goyal wrote:
> On Thu, Apr 26, 2012 at 02:59:11PM -0700, Tejun Heo wrote:
> > When policy data allocation fails in the middle, blkg_alloc() invokes
> > blkg_free() to destroy the half constructed blkg. This ends up
> > calling pd_exit_fn() on policy datas which didn't go through
> > pd_init_fn(). Fix it by making blkg_alloc() call pd_init_fn()
> > immediately after each policy data allocation.
> >
> > Signed-off-by: Tejun Heo <tj@kernel.org>
> > Cc: Vivek Goyal <vgoyal@redhat.com>
> > ---
> > block/blk-cgroup.c | 6 +-----
> > 1 files changed, 1 insertions(+), 5 deletions(-)
> >
> > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> > index 02cf633..4ab7420 100644
> > --- a/block/blk-cgroup.c
> > +++ b/block/blk-cgroup.c
> > @@ -125,12 +125,8 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q)
> >
> > blkg->pd[i] = pd;
> > pd->blkg = blkg;
> > - }
> > -
> > - /* invoke per-policy init */
> > - for (i = 0; i < BLKCG_MAX_POLS; i++) {
> > - struct blkcg_policy *pol = blkcg_policy[i];
> >
> > + /* invoke per-policy init */
> > if (blkcg_policy_enabled(blkg->q, pol))
> > pol->pd_init_fn(blkg);
>
> Deja Vu. In one of the mails I had said that how about moving init_fn
> in upper loop and get rid of for loop below. Then retracted it saying
> probably you wanted to allocate all the groups first before calling
> init functions of individual policies. Here we are back again for a
> different reason though. :-)

Heh, yeah, should have updated it then. :)

--
tejun