From: Keith Busch <kbusch@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-nvme@lists.infradead.org, hch@lst.de,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
sagi@grimberg.me
Subject: Re: [PATCH V3 02/10] nvme-core: use xarray for ctrl ns tracking
Date: Tue, 14 Jul 2020 18:41:51 -0700 [thread overview]
Message-ID: <20200715014151.GD2772284@dhcp-10-100-145-180.wdl.wdc.com> (raw)
In-Reply-To: <20200715013342.GD12769@casper.infradead.org>
On Wed, Jul 15, 2020 at 02:33:42AM +0100, Matthew Wilcox wrote:
> On Tue, Jul 14, 2020 at 05:55:09PM -0700, Keith Busch wrote:
> > On Tue, Jul 14, 2020 at 04:30:49PM -0700, Chaitanya Kulkarni wrote:
> > > @@ -3933,9 +3918,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
> > > blk_integrity_unregister(ns->disk);
> > > }
> > >
> > > - down_write(&ns->ctrl->namespaces_rwsem);
> > > - list_del_init(&ns->list);
> > > - up_write(&ns->ctrl->namespaces_rwsem);
> > > + xa_erase(xa, ns->head->ns_id);
> >
> > Since you're using rcu to protect the kref_get() on load, we need a
> > synchronize_rcu() after removing it from the xarray.
>
> No, synchronize_rcu() is expensive. We should instead use call_rcu()
> to free the ns once the refcount hits zero.
Yeah, that is an even better option, though namespace removal is so
infrequent that cost isn't really a concern: this function already calls
synchronize_rcu() and syncronize_srcu().
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next prev parent reply other threads:[~2020-07-15 1:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-14 23:30 [PATCH V3 00/10] nvme: use xarray for ns tracking Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 01/10] xarray: add __xa_load() version Chaitanya Kulkarni
2020-07-15 0:46 ` Keith Busch
2020-07-15 0:47 ` Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 02/10] nvme-core: use xarray for ctrl ns tracking Chaitanya Kulkarni
2020-07-15 0:55 ` Keith Busch
2020-07-15 1:33 ` Matthew Wilcox
2020-07-15 1:41 ` Keith Busch [this message]
2020-07-15 5:12 ` Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 03/10] nvme: centralize queue action nvme_kill_queues() Chaitanya Kulkarni
2020-07-15 1:36 ` Keith Busch
2020-07-15 1:39 ` Matthew Wilcox
2020-07-15 7:11 ` Christoph Hellwig
2020-07-14 23:30 ` [PATCH V3 04/10] nvme: centralize queue action nvme_unfreeze() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 05/10] nvme: centralize queue action nvme_wait_freeze() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 06/10] nvme: centralize queue action nvme_start_freeze() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 07/10] nvme: centralize queue action nvme_stop_queues() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 08/10] nvme: centralize queue action nvme_start_queues() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 09/10] nvme: centralize queue action nvme_sync_queues() Chaitanya Kulkarni
2020-07-14 23:30 ` [PATCH V3 10/10] nvmet: use xarray for ctrl ns storing Chaitanya Kulkarni
2020-07-15 7:10 ` Christoph Hellwig
2020-07-17 1:52 ` Chaitanya Kulkarni
2020-07-15 7:03 ` [PATCH V3 00/10] nvme: use xarray for ns tracking Christoph Hellwig
2020-07-16 1:48 ` Chaitanya Kulkarni
2020-07-17 2:02 ` Chaitanya Kulkarni
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