From nobody Mon Apr 6 13:28:24 2026 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 0C1D3C433F5 for ; Thu, 29 Sep 2022 22:55:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229791AbiI2Wzw (ORCPT ); Thu, 29 Sep 2022 18:55:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229744AbiI2WzZ (ORCPT ); Thu, 29 Sep 2022 18:55:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98E3AD74D6; Thu, 29 Sep 2022 15:55:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6F208621DE; Thu, 29 Sep 2022 22:55:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48B05C433C1; Thu, 29 Sep 2022 22:55:23 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1oe2SL-000coF-0d; Thu, 29 Sep 2022 18:56:37 -0400 Message-ID: <20220929225636.815153112@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 29 Sep 2022 18:55:48 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , stable@vger.kernel.org Subject: [for-next][PATCH 06/15] tracing: Wake up ring buffer waiters on closing of the file References: <20220929225542.784716766@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" When the file that represents the ring buffer is closed, there may be waiters waiting on more input from the ring buffer. Call ring_buffer_wake_waiters() to wake up any waiters when the file is closed. Link: https://lkml.kernel.org/r/20220927231825.182416969@goodmis.org Cc: stable@vger.kernel.org Cc: Ingo Molnar Cc: Andrew Morton Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice") Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_events.h | 1 + kernel/trace/trace.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 8401dec93c15..20749bd9db71 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -92,6 +92,7 @@ struct trace_iterator { unsigned int temp_size; char *fmt; /* modified format holder */ unsigned int fmt_size; + long wait_index; =20 /* trace_seq for __print_flags() and __print_symbolic() etc. */ struct trace_seq tmp_seq; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index aed7ea6e6045..e101b0764b39 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8160,6 +8160,12 @@ static int tracing_buffers_release(struct inode *ino= de, struct file *file) =20 __trace_array_put(iter->tr); =20 + iter->wait_index++; + /* Make sure the waiters see the new wait_index */ + smp_wmb(); + + ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file); + if (info->spare) ring_buffer_free_read_page(iter->array_buffer->buffer, info->spare_cpu, info->spare); @@ -8313,6 +8319,8 @@ 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; =20 @@ -8320,10 +8328,17 @@ tracing_buffers_splice_read(struct file *file, loff= _t *ppos, if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) goto out; =20 + wait_index =3D READ_ONCE(iter->wait_index); + ret =3D wait_on_pipe(iter, iter->tr->buffer_percent); if (ret) goto out; =20 + /* Make sure we see the new wait_index */ + smp_rmb(); + if (wait_index !=3D iter->wait_index) + goto out; + goto again; } =20 --=20 2.35.1