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[23.128.96.36]) by mx.google.com with ESMTPS id a63-20020a639042000000b005b7dd1d190asi99511pge.263.2023.10.16.13.36.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Oct 2023 13:36:23 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) client-ip=23.128.96.36; Authentication-Results: mx.google.com; dkim=pass header.i=@nabijaczleweli.xyz header.s=202305 header.b=jYyfhEbJ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nabijaczleweli.xyz Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by pete.vger.email (Postfix) with ESMTP id 8117C80BCBBD; Mon, 16 Oct 2023 13:36:17 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at pete.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234164AbjJPUgF (ORCPT + 18 others); Mon, 16 Oct 2023 16:36:05 -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-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20231006 X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on pete.vger.email To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (pete.vger.email [0.0.0.0]); Mon, 16 Oct 2023 13:36:17 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779945788622854908 X-GMAIL-MSGID: 1779945788622854908 Otherwise we risk sleeping with the pipe locked for indeterminate lengths of time. Link: https://lore.kernel.org/linux-fsdevel/qk6hjuam54khlaikf2ssom6custxf5is2ekkaequf4hvode3ls@zgf7j5j4ubvw/t/#u Signed-off-by: Ahelenia Ziemiańska --- 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; - again: trace_access_lock(iter->cpu_file); entries = ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu_file); @@ -8528,35 +8527,12 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, /* did we read anything? */ if (!spd.nr_pages) { - long wait_index; - - if (ret) - goto out; - - ret = -EAGAIN; - if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) - goto out; - - wait_index = READ_ONCE(iter->wait_index); - - ret = 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 != iter->wait_index) - goto out; - - goto again; + if (!ret) + ret = -EAGAIN; + } else { + ret = splice_to_pipe(pipe, &spd); } - ret = splice_to_pipe(pipe, &spd); -out: splice_shrink_spd(&spd); return ret;