From: Yonghong Song <yonghong.song@linux.dev>
To: Oleg Nesterov <oleg@redhat.com>, Alexei Starovoitov <ast@kernel.org>
Cc: Chuyi Zhou <zhouchuyi@bytedance.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kui-Feng Lee <kuifeng@fb.com>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH 2/3] bpf: bpf_iter_task_next: use __next_thread() rather than next_thread()
Date: Wed, 15 Nov 2023 22:34:10 -0500 [thread overview]
Message-ID: <95c2b494-ce8a-422b-918e-8ae4853ab9f0@linux.dev> (raw)
In-Reply-To: <20231114163237.GA897@redhat.com>
On 11/14/23 11:32 AM, Oleg Nesterov wrote:
> Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c
> is the last user and the usage is wrong.
>
> bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never
> happen if kit->pos execs. Change this code to use __next_thread().
>
> With or without this change the usage of kit->pos/task and next_task()
> doesn't look nice, see the next patch.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2023-11-16 3:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-14 16:32 [PATCH 0/3] bpf: kernel/bpf/task_iter.c: don't abuse next_thread() Oleg Nesterov
2023-11-14 16:32 ` [PATCH 1/3] bpf: task_group_seq_get_next: use __next_thread() rather than next_thread() Oleg Nesterov
2023-11-16 3:31 ` Yonghong Song
2023-11-16 9:34 ` Oleg Nesterov
2023-11-16 11:46 ` Yonghong Song
2023-11-14 16:32 ` [PATCH 2/3] bpf: bpf_iter_task_next: " Oleg Nesterov
2023-11-16 3:34 ` Yonghong Song [this message]
2023-11-14 16:32 ` [PATCH 3/3] bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) Oleg Nesterov
2023-11-16 5:16 ` Yonghong Song
2023-11-16 9:38 ` Oleg Nesterov
2023-11-16 3:13 ` [PATCH 0/3] bpf: kernel/bpf/task_iter.c: don't abuse next_thread() Yonghong Song
2023-11-16 9:54 ` Oleg Nesterov
2023-11-16 11:52 ` Yonghong Song
2023-11-19 20:00 ` patchwork-bot+netdevbpf
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