From nobody Wed Dec 17 09:46:12 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3AE1CDB474 for ; Mon, 16 Oct 2023 20:36:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234211AbjJPUgG (ORCPT ); Mon, 16 Oct 2023 16:36:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234210AbjJPUf7 (ORCPT ); Mon, 16 Oct 2023 16:35:59 -0400 Received: from tarta.nabijaczleweli.xyz (tarta.nabijaczleweli.xyz [139.28.40.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1EE35F9; Mon, 16 Oct 2023 13:35:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nabijaczleweli.xyz; s=202305; t=1697488545; bh=M3/tVO1jPiOOO1Rw82ko0E0+3twLTEqXefGMw9ogJ9c=; h=Date:From:Cc:Subject:References:In-Reply-To:From; b=jYyfhEbJKEMbOcqostzxf+q73l4ZaJN6lOf9bdtVSWBOPf+msOlGFpNFJVUsC6+QG 4wJk7QZj/bAAHrNWwhLZuaEVwhM5Iau+GJ3ojMT0KmcjbZoVDP8Skr8cgtWqiuJHNN pMZ7Lvlf8sfXBY000Uy1ucYtx/WVcKldmqPDCM1xc0Ewjiq3/kxnKcdUStKYsI5EZQ g1tOMXu8arK3rnoQylY8ZPA5AvYphy71K/rwO1J1Qs3jVbucbNUusKHp5iPIlf3PZP Ten/sO9sDaOD7Sh0aRYfwshmiwXykfQDyItYBVGMYi+QjMKL0/38X1D1bhgw/zCn5S wXaLEXXF1FoVw== Received: from tarta.nabijaczleweli.xyz (unknown [192.168.1.250]) by tarta.nabijaczleweli.xyz (Postfix) with ESMTPSA id 4B34D10410; Mon, 16 Oct 2023 22:35:45 +0200 (CEST) Date: Mon, 16 Oct 2023 22:35:45 +0200 From: Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= Cc: Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH 04/11] tracing: tracing_buffers_splice_read: behave as-if non-blocking I/O Message-ID: <1b84f2e4e5eaad501ff7b2bb03e2ad2f25ecdf14.1697486714.git.nabijaczleweli@nabijaczleweli.xyz> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="jnbdnpt6gizqlzrj" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20231006 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --jnbdnpt6gizqlzrj Content-Disposition: inline Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Otherwise we risk sleeping with the pipe locked for indeterminate lengths of time. Link: https://lore.kernel.org/linux-fsdevel/qk6hjuam54khlaikf2ssom6custxf5i= s2ekkaequf4hvode3ls@zgf7j5j4ubvw/t/#u Signed-off-by: Ahelenia Ziemia=C5=84ska --- kernel/trace/trace.c | 32 ++++---------------------------- 1 file changed, 4 insertions(+), 28 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index abaaf516fcae..9be7a4c0a3ca 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8477,7 +8477,6 @@ tracing_buffers_splice_read(struct file *file, loff_t= *ppos, if (splice_grow_spd(pipe, &spd)) return -ENOMEM; =20 - again: trace_access_lock(iter->cpu_file); entries =3D ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu= _file); =20 @@ -8528,35 +8527,12 @@ tracing_buffers_splice_read(struct file *file, loff= _t *ppos, =20 /* did we read anything? */ if (!spd.nr_pages) { - long wait_index; - - if (ret) - goto out; - - ret =3D -EAGAIN; - if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) - goto out; - - wait_index =3D READ_ONCE(iter->wait_index); - - ret =3D wait_on_pipe(iter, iter->tr->buffer_percent); - if (ret) - goto out; - - /* No need to wait after waking up when tracing is off */ - if (!tracer_tracing_is_on(iter->tr)) - goto out; - - /* Make sure we see the new wait_index */ - smp_rmb(); - if (wait_index !=3D iter->wait_index) - goto out; - - goto again; + if (!ret) + ret =3D -EAGAIN; + } else { + ret =3D splice_to_pipe(pipe, &spd); } =20 - ret =3D splice_to_pipe(pipe, &spd); -out: splice_shrink_spd(&spd); =20 return ret; --=20 2.39.2 --jnbdnpt6gizqlzrj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfWlHToQCjFzAxEFjvP0LAY0mWPEFAmUtnqAACgkQvP0LAY0m WPEmqw/9F+86jAT/+cOAKyJ5dowTlCTtI+SGP8lbyGOvjoWqxtxJDm3/GLDyPyP0 5QGkE1/eUjJJ7TsN+qqQk2Ykgc+pi0cx/QYXVNEhh9lvmN6l7K0MfNqtDsQdAV8Y V0umad0M411VJHUMUxqKh6eTj+U6Q9Ie37xi+6WiBXdArobvqGtS5aVhPsu80zgO N6CP+px0KJ0atkrMcZCHfljwDM/x+xLWUs3OvV4yfnhlx3Y4OaKahlJ+U+T5mgXD jpQb830Emc97eQptnBk/LKoGC/jfHZQQrIM7ECXFSRog5OQXm9ly7N+iHOU7L0fq KBXD1A6g6dEMwEJktFTST+tcxUlLe4S/G4BayYvrVKec+9k6AAD9TGcErBO8u698 OexL1N3Aok0s1GZTUe7bWe3550Zw/pKYY9ZX1MtvDsCJNXadqZKyPr0CVXUfINpr kJvVyEePVzxoSanJ8jR6/8cPHSSFnMioN+Ed7OYVQAOsOpnPQFc3hq1tSYjqgQJV 1nakzp7vzt/gysy5kokfq7yYvTEcCmaJVXqvUgk77jUntoM52vQl5ztLolvXaQTO Q4YWomGl++BNEa0EIIGIMdA0feFKCby0d5+SMACBz0SjQWnTcl248O+1WP7+kBx1 HUvkIZfScVZZPHfk30F63Aq2cLmLNV0Cw7DPpa4G9tGhuBWNoTo= =RqPS -----END PGP SIGNATURE----- --jnbdnpt6gizqlzrj--