I don't see a complete design proposal here. Can you clarify the fuller
picture of what you're proposing to do?
Matt
----- Original Message -----
> From: "Satya Prakash GS" <g.satyaprak...@gmail.com>
> To: "Matt Benjamin" <mbenja...@redhat.com>, "Malahal Naineni"
> <mala...@gmail.com>,
> nfs-ganesha-devel@lists.sourceforge.net
> Sent: Wednesday, May 3, 2017 4:14:21 PM
> Subject: Re: [Nfs-ganesha-devel] reg. drc nested locks
>
> Thank you for the quick reply.
>
> In dupreq_finish, as part of retiring the drc quite a few locks are
> acquired and dropped (per entry). I want to fix a bug where drc retire
> will happen as part of a different function (this will be called from
> free_expired). The existing logic gets carried over to the new
> function and I was thinking that we may not have to acquire and
> release lock so many times.
>
> Thanks,
> Satya.
>
> On Thu, May 4, 2017 at 1:21 AM, Matt Benjamin <mbenja...@redhat.com> wrote:
> > Hi Satya,
> >
> > Sorry, my recommendation would be, we do not change locking to be more
> > coarse grained, and in general, should update it in response to an
> > indication that it is incorrect, not to improve readability in the first
> > instance.
> >
> > Regards,
> >
> > Matt
> >
> > ----- Original Message -----
> >> From: "Matt Benjamin" <mbenja...@redhat.com>
> >> To: "Satya Prakash GS" <g.satyaprak...@gmail.com>
> >> Cc: nfs-ganesha-devel@lists.sourceforge.net, "Malahal Naineni"
> >> <mala...@gmail.com>
> >> Sent: Wednesday, May 3, 2017 3:43:06 PM
> >> Subject: Re: [Nfs-ganesha-devel] reg. drc nested locks
> >>
> >> No?
> >>
> >> Matt
> >>
> >> ----- Original Message -----
> >> > From: "Satya Prakash GS" <g.satyaprak...@gmail.com>
> >> > To: nfs-ganesha-devel@lists.sourceforge.net, "Malahal Naineni"
> >> > <mala...@gmail.com>
> >> > Sent: Wednesday, May 3, 2017 3:34:31 PM
> >> > Subject: [Nfs-ganesha-devel] reg. drc nested locks
> >> >
> >> > Hi,
> >> >
> >> > In nfs_dupreq_start and nfs_dupreq_finish when allocating/freeing a
> >> > dupreq_entry we are trying hard to keep both dupreq_q and the rbtree
> >> > in sync acquiring both the partition lock and the drc (t->mtx,
> >> > drc->mtx). This requires dropping and reacquiring locks at certain
> >> > places. Can these nested locks be changed to take locks one after the
> >> > other.
> >> >
> >> > For example at the time of allocation, we could choose to do this -
> >> >
> >> > PTHREAD_MUTEX_lock(&t->mtx); /* partition lock */
> >> > nv = rbtree_x_cached_lookup(&drc->xt, t, &dk->rbt_k, dk->hk);
> >> > if (!nv) {
> >> > dk->refcnt = 2;
> >> > (void)rbtree_x_cached_insert(&drc->xt, t,
> >> > &dk->rbt_k, dk->hk);
> >> > PTHREAD_MUTEX_unlock(&t->mtx); /* partition lock */
> >> >
> >> > PTHREAD_MUTEX_lock(&drc->mtx);
> >> > TAILQ_INSERT_TAIL(&drc->dupreq_q, dk, fifo_q);
> >> > ++(drc->size);
> >> > PTHREAD_MUTEX_unlock(&drc->mtx);
> >> > }
> >> >
> >> > I am assuming this would simplify the lock code a lot.
> >> > If there is a case where this would introduce a race please let me know.
> >> >
> >> > Thanks,
> >> > Satya.
> >> >
> >> > ------------------------------------------------------------------------------
> >> > Check out the vibrant tech community on one of the world's most
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> >> > _______________________________________________
> >> > Nfs-ganesha-devel mailing list
> >> > Nfs-ganesha-devel@lists.sourceforge.net
> >> > https://lists.sourceforge.net/lists/listinfo/nfs-ganesha-devel
> >> >
> >>
> >> --
> >> Matt Benjamin
> >> Red Hat, Inc.
> >> 315 West Huron Street, Suite 140A
> >> Ann Arbor, Michigan 48103
> >>
> >> http://www.redhat.com/en/technologies/storage
> >>
> >> tel. 734-821-5101
> >> fax. 734-769-8938
> >> cel. 734-216-5309
> >>
> >
> > --
> > Matt Benjamin
> > Red Hat, Inc.
> > 315 West Huron Street, Suite 140A
> > Ann Arbor, Michigan 48103
> >
> > http://www.redhat.com/en/technologies/storage
> >
> > tel. 734-821-5101
> > fax. 734-769-8938
> > cel. 734-216-5309
>
--
Matt Benjamin
Red Hat, Inc.
315 West Huron Street, Suite 140A
Ann Arbor, Michigan 48103
http://www.redhat.com/en/technologies/storage
tel. 734-821-5101
fax. 734-769-8938
cel. 734-216-5309
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