From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
Li Zefan <lizefan@huawei.com>,
Angelo Ruocco <angeloruocco90@gmail.com>,
Dennis Zhou <dennis@kernel.org>,
Josef Bacik <josef@toxicpanda.com>,
Liu Bo <bo.liu@linux.alibaba.com>,
Bart Van Assche <bvanassche@acm.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org, bfq-iosched@googlegroups.com,
oleksandr@natalenko.name, cgroups@vger.kernel.org,
linux-doc@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>
Subject: Re: [PATCH 01/12] kernfs: add function to find kernfs_node without increasing ref counter
Date: Mon, 12 Nov 2018 04:28:40 -0800 [thread overview]
Message-ID: <20181112122840.GA1429@kroah.com> (raw)
In-Reply-To: <20181112095632.69114-2-paolo.valente@linaro.org>
On Mon, Nov 12, 2018 at 10:56:21AM +0100, Paolo Valente wrote:
> From: Angelo Ruocco <angeloruocco90@gmail.com>
>
> The kernfs pseudo file system doesn't export any function to only find
> a node by name, without also getting a reference on it.
> But in some cases it is useful to just locate a kernfs node, while
> using it or not depends on some other condition.
>
> This commit adds a function to just look for a node, without getting
> a reference on it.
Eeek, that sounds really bad. So you save off a pointer to something,
and have no idea if that pointer now really is valid or not? It can
instantly disappear right afterwards.
This feels wrong, what is the problem of having a properly reference
counted object passed back to you that you have to create a dangerous
function like this?
greg k-h
next prev parent reply other threads:[~2018-11-12 12:28 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 9:56 [PATCH 00/12] unify the interface of the proportional-share policy in blkio/io Paolo Valente
2018-11-12 9:56 ` [PATCH 01/12] kernfs: add function to find kernfs_node without increasing ref counter Paolo Valente
2018-11-12 12:28 ` Greg Kroah-Hartman [this message]
2018-11-13 1:56 ` Matthew Wilcox
2018-11-13 17:53 ` Paolo Valente
2018-11-13 19:35 ` Greg Kroah-Hartman
2018-11-12 9:56 ` [PATCH 02/12] cgroup: add hook seq_show_cft with also the owning cftype as parameter Paolo Valente
2018-11-12 9:56 ` [PATCH 03/12] block, cgroup: pass cftype to functions that need to use it Paolo Valente
2018-11-12 9:56 ` [PATCH 04/12] cgroup: link cftypes of the same subsystem with the same name Paolo Valente
2018-11-12 9:56 ` [PATCH 05/12] cgroup: add owner name to cftypes Paolo Valente
2018-11-12 9:56 ` [PATCH 06/12] block, bfq: align min and default weights with cfq Paolo Valente
2018-11-12 9:56 ` [PATCH 07/12] cgroup: make all functions of all cftypes be invoked Paolo Valente
2018-11-12 9:56 ` [PATCH 08/12] block, cfq: allow cgroup files to be shared Paolo Valente
2018-11-12 9:56 ` [PATCH 09/12] block, bfq: use standard file names for the proportional-share policy Paolo Valente
2018-11-12 9:56 ` [PATCH 10/12] block, throttle: allow sharing cgroup statistic files Paolo Valente
2018-11-12 9:56 ` [PATCH 11/12] doc, bfq-iosched: fix a few clerical errors Paolo Valente
2018-11-12 9:56 ` [PATCH 12/12] doc, bfq-iosched: make it consistent with the new cgroup interface Paolo Valente
2018-11-12 9:58 ` [PATCH 00/12] unify the interface of the proportional-share policy in blkio/io Paolo Valente
2018-11-12 10:00 ` Oleksandr Natalenko
2018-11-12 10:14 ` Oleksandr Natalenko
2018-11-12 10:17 ` Paolo Valente
2018-11-12 15:35 ` Jens Axboe
2018-11-12 15:45 ` Paolo Valente
2018-11-12 15:48 ` Jens Axboe
2018-11-12 15:54 ` Josef Bacik
2018-11-12 16:05 ` Jens Axboe
2018-11-15 11:54 ` Angelo Ruocco
[not found] ` <CADiTV-3tSpEMG7EHz3XGvfekNdtN8k_KQiDMtyykgOb81cvO0g@mail.gmail.com>
2018-11-15 15:42 ` Oleksandr Natalenko
2018-11-15 16:30 ` Jens Axboe
2018-11-19 9:46 ` Angelo Ruocco
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