From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, kernel-team@fb.com
Subject: Re: [PATCH v4 bpf-next 2/6] bpf: prevent deadlock from recursive bpf_task_storage_[get|delete]
Date: Tue, 23 Feb 2021 12:06:22 +0100 [thread overview]
Message-ID: <YDThrlixVqfHP7I9@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210223012014.2087583-3-songliubraving@fb.com>
On Mon, Feb 22, 2021 at 05:20:10PM -0800, Song Liu wrote:
> BPF helpers bpf_task_storage_[get|delete] could hold two locks:
> bpf_local_storage_map_bucket->lock and bpf_local_storage->lock. Calling
> these helpers from fentry/fexit programs on functions in bpf_*_storage.c
> may cause deadlock on either locks.
>
> Prevent such deadlock with a per cpu counter, bpf_task_storage_busy, which
> is similar to bpf_prog_active. We need this counter to be global, because
So bpf_prog_active is one of the biggest turds around, and now you're
making it worse ?!
next prev parent reply other threads:[~2021-02-23 11:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 1:20 [PATCH v4 bpf-next 0/6] bpf: enable task local storage for tracing programs Song Liu
2021-02-23 1:20 ` [PATCH v4 bpf-next 1/6] " Song Liu
2021-02-23 3:08 ` kernel test robot
2021-02-23 3:08 ` kernel test robot
2021-02-23 4:04 ` kernel test robot
2021-02-23 4:04 ` kernel test robot
2021-02-23 19:23 ` Martin KaFai Lau
2021-02-23 20:51 ` Song Liu
2021-02-23 1:20 ` [PATCH v4 bpf-next 2/6] bpf: prevent deadlock from recursive bpf_task_storage_[get|delete] Song Liu
2021-02-23 6:21 ` Andrii Nakryiko
2021-02-23 7:16 ` Song Liu
2021-02-23 7:19 ` Andrii Nakryiko
2021-02-23 16:44 ` Alexei Starovoitov
2021-02-23 11:06 ` Peter Zijlstra [this message]
2021-02-23 20:49 ` Song Liu
2021-02-23 1:20 ` [PATCH v4 bpf-next 3/6] selftests/bpf: add non-BPF_LSM test for task local storage Song Liu
2021-02-23 1:20 ` [PATCH v4 bpf-next 4/6] selftests/bpf: test deadlock from recursive bpf_task_storage_[get|delete] Song Liu
2021-02-23 1:20 ` [PATCH v4 bpf-next 5/6] bpf: runqslower: prefer using local vmlimux to generate vmlinux.h Song Liu
2021-02-23 6:26 ` Andrii Nakryiko
2021-02-23 21:24 ` Martin KaFai Lau
2021-02-23 1:20 ` [PATCH v4 bpf-next 6/6] bpf: runqslower: use task local storage Song Liu
2021-02-23 21:33 ` Martin KaFai Lau
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