Received-SPF: pass (google.com: domain of linux-kernel+bounces-136185-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Precedence: bulk
MIME-Version: 1.0
References: <20240408-hid-bpf-sleepable-v6-0-0499ddd91b94@kernel.org>
 <20240408-hid-bpf-sleepable-v6-6-0499ddd91b94@kernel.org> <345cddbdfe8e91dc6395331c838329d02d519863.camel@gmail.com>
In-Reply-To: <345cddbdfe8e91dc6395331c838329d02d519863.camel@gmail.com>
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Mon, 8 Apr 2024 20:16:43 -0700
Message-ID: <CAADnVQ+AOtxrQ6Oai20CmU=MSW3f+d_ykRZehYdK=pYjBDdYnQ@mail.gmail.com>
Subject: Re: [PATCH RFC bpf-next v6 6/6] selftests/bpf: add sleepable timer tests
To: Eduard Zingerman <eddyz87@gmail.com>
Cc: Benjamin Tissoires <bentiss@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 <yonghong.song@linux.dev>, John Fastabend <john.fastabend@gmail.com>, 
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>, 
	Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>, 
	bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Mon, Apr 8, 2024 at 4:01=E2=80=AFPM Eduard Zingerman <eddyz87@gmail.com>=
 wrote:
>
> > +SEC("tc")
> > +/* check that calling bpf_timer_start() with a delay on a sleepable
> > + * callback is returning -EINVAL
> > + */
> > +__retval(-22)
> > +long test_call_sleepable_delay(void *ctx)
> > +{
> > +     int key =3D 2;
> > +     struct bpf_timer *timer;
> > +
> > +     timer =3D bpf_map_lookup_elem(&timer_map, &key);
> > +     if (!timer)
> > +             return 1;
> > +
> > +     if (bpf_timer_init(timer, &timer_map, CLOCK_MONOTONIC | BPF_F_TIM=
ER_SLEEPABLE))
> > +             return 2;
> > +
> > +     if (bpf_timer_set_sleepable_cb(timer, timer_cb_sleepable))
> > +             return 3;
> > +
> > +     return bpf_timer_start(timer, 1, 0);
>
> Q: should verifier statically check that 3rd parameter is zero for sleepa=
ble timers?
>   (same question for call to bpf_timer_set_sleepable_cb() with non-sleepa=
ble map)

It can, but that sounds like more work for the verifier.
Which gives more reasons to use new kfuncs and clean start with bpf_wq.