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From: Daniel Borkmann <daniel@iogearbox.net>
To: Y Song <ys114321@gmail.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alban Crequy <alban.crequy@gmail.com>,
	netdev <netdev@vger.kernel.org>,
	linux-kernel@vger.kernel.org,
	containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
	Alban Crequy <alban@kinvolk.io>,
	tj@kernel.org
Subject: Re: [PATCH] [RFC] bpf: tracing: new helper bpf_get_current_cgroup_ino
Date: Wed, 23 May 2018 10:57:06 +0200	[thread overview]
Message-ID: <ef833a5c-8307-fee7-26ec-057f623a9049@iogearbox.net> (raw)
In-Reply-To: <CAH3MdRVwmKd84ePvNX+NuAj3TfA_28BObEmzBqGXv=P5_A=8fQ@mail.gmail.com>

On 05/23/2018 06:31 AM, Y Song wrote:
> On Tue, May 22, 2018 at 8:35 PM, Alexei Starovoitov
> <alexei.starovoitov@gmail.com> wrote:
>> On Tue, May 22, 2018 at 08:33:24PM -0700, Y Song wrote:
>>> +       struct cgroup *cgrp = task_dfl_cgroup(current);
>>> +       if (!cgrp)
>>> +               return -EINVAL;
>>
>> why this check is needed?
> 
> No reason :-) Originally I am concerned whether it is possible cgrp
> could be NULL.
> By looking at the code, it SEEMS to me that it could not be NULL, but I am not
> 100% sure (as I am not a cgroup expert). Since you are asking,
> probably means it cannot be NULL, so will remove it in formal upstream patch.

Aside from this the cgrp->kn->id.id is also u64, so overlapping this with
error codes we'll get into a similar issue as with bpf_perf_event_read().

  reply	other threads:[~2018-05-23  8:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-13 17:33 Alban Crequy
2018-05-14 19:38 ` Y Song
2018-05-21 13:52   ` Alban Crequy
2018-05-21 16:26 ` Alexei Starovoitov
2018-05-22  0:24   ` Y Song
2018-05-23  3:33     ` Y Song
2018-05-23  3:35       ` Alexei Starovoitov
2018-05-23  4:31         ` Y Song
2018-05-23  8:57           ` Daniel Borkmann [this message]
2018-05-25 15:21       ` Alban Crequy
2018-05-25 16:28         ` Y Song

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