From: "Paul E. McKenney" <paulmck@kernel.org>
To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
Ankur Arora <ankur.a.arora@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
kernel-team@meta.com
Subject: [PATCH RFC bpf] Chose RCU Tasks based on TASKS_RCU rather than PREEMPTION
Date: Wed, 28 Feb 2024 11:41:29 -0800 [thread overview]
Message-ID: <847ac98b-886d-4f91-b961-2bb452555af0@paulmck-laptop> (raw)
The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that
even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY
might see the occasional preemption, and that this preemption just might
happen within a trampoline.
Therefore, update bpf_tramp_image_put() to choose call_rcu_tasks()
based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION.
This change might enable further simplifications, but the goal of this
effort is to make the code safe, not necessarily optimal.
Only build tested.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <bpf@vger.kernel.org>
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index d382f5ebe06c8..5085f66b33890 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -333,7 +333,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im)
int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP,
NULL, im->ip_epilogue);
WARN_ON(err);
- if (IS_ENABLED(CONFIG_PREEMPTION))
+ if (IS_ENABLED(CONFIG_TASKS_RCU))
call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks);
else
percpu_ref_kill(&im->pcref);
reply other threads:[~2024-02-28 19:41 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=847ac98b-886d-4f91-b961-2bb452555af0@paulmck-laptop \
--to=paulmck@kernel.org \
--cc=andrii@kernel.org \
--cc=ankur.a.arora@oracle.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=haoluo@google.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kernel-team@meta.com \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.lau@linux.dev \
--cc=sdf@google.com \
--cc=song@kernel.org \
--cc=tglx@linutronix.de \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).