From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
To: Hao Luo <haoluo@google.com>
Cc: Hou Tao <houtao@huaweicloud.com>,
Waiman Long <longman@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
netdev@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Jiri Olsa <jolsa@kernel.org>,
bpf <bpf@vger.kernel.org>,
"houtao1@huawei.com" <houtao1@huawei.com>,
LKML <linux-kernel@vger.kernel.org>,
Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [net-next] bpf: avoid hashtab deadlock with try_lock
Date: Wed, 30 Nov 2022 13:56:18 +0800 [thread overview]
Message-ID: <CAMDZJNVEnYeqj1-ZcfJHwz4ZSVBA5H46_jMEkLxRgkgQ4R=Gaw@mail.gmail.com> (raw)
In-Reply-To: <CA+khW7hsvueaRRFX3m-gxtW0A7fYEOJLfDTSTVMY-OLn_si1hQ@mail.gmail.com>
On Wed, Nov 30, 2022 at 1:02 PM Hao Luo <haoluo@google.com> wrote:
>
> On Tue, Nov 29, 2022 at 8:13 PM Hou Tao <houtao@huaweicloud.com> wrote:
> >
> > On 11/30/2022 10:47 AM, Tonghao Zhang wrote:
> <...>
> > > if (in_nmi()) {
> > > if (!raw_spin_trylock_irqsave(&b->raw_lock, flags))
> > > return -EBUSY;
> >
> > The only purpose of trylock here is to make lockdep happy and it may lead to
> > unnecessary -EBUSY error for htab operations in NMI context. I still prefer add
> > a virtual lock-class for map_locked to fix the lockdep warning. So could you use
> > separated patches to fix the potential dead-lock and the lockdep warning ? It
> > will be better you can also add a bpf selftests for deadlock problem as said before.
> >
>
> Agree with Tao here. Tonghao, could you send another version which:
>
> - separates the fix to deadlock and the fix to lockdep warning
> - includes a bpf selftest to verify the fix to deadlock
> - with bpf-specific tag: [PATCH bpf-next]
>
> There are multiple ideas on the fly in this thread, it's easy to lose
> track of what has been proposed and what change you intend to make.
Hi, I will send v2 soon. Thanks.
> Thanks,
> Hao
--
Best regards, Tonghao
next prev parent reply other threads:[~2022-11-30 5:57 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 10:05 [net-next] bpf: avoid the multi checking xiangxia.m.yue
2022-11-21 10:05 ` [net-next] bpf: avoid hashtab deadlock with try_lock xiangxia.m.yue
2022-11-21 20:19 ` Jakub Kicinski
2022-11-22 1:15 ` Hou Tao
2022-11-22 3:12 ` Tonghao Zhang
2022-11-22 4:01 ` Hou Tao
2022-11-22 4:06 ` Hou Tao
2022-11-24 12:57 ` Tonghao Zhang
2022-11-24 14:13 ` Hou Tao
2022-11-28 3:15 ` Tonghao Zhang
2022-11-28 21:55 ` Hao Luo
2022-11-29 4:32 ` Hou Tao
2022-11-29 6:06 ` Tonghao Zhang
2022-11-29 7:56 ` Hou Tao
2022-11-29 12:45 ` Hou Tao
2022-11-29 16:06 ` Waiman Long
2022-11-29 17:23 ` Boqun Feng
2022-11-29 17:32 ` Boqun Feng
2022-11-29 19:36 ` Hao Luo
2022-11-29 21:13 ` Waiman Long
2022-11-30 1:50 ` Hou Tao
2022-11-30 2:47 ` Tonghao Zhang
2022-11-30 3:06 ` Waiman Long
2022-11-30 3:32 ` Tonghao Zhang
2022-11-30 4:07 ` Waiman Long
2022-11-30 4:13 ` Hou Tao
2022-11-30 5:02 ` Hao Luo
2022-11-30 5:56 ` Tonghao Zhang [this message]
2022-11-30 5:55 ` Tonghao Zhang
2022-12-01 2:53 ` Hou Tao
2022-11-30 1:37 ` Hou Tao
2022-11-22 22:16 ` [net-next] bpf: avoid the multi checking Daniel Borkmann
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