From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759600Ab3LFXqF (ORCPT ); Fri, 6 Dec 2013 18:46:05 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:48511 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161880Ab3LFXPG (ORCPT ); Fri, 6 Dec 2013 18:15:06 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Anton Blanchard , Benjamin Herrenschmidt , Kamal Mostafa Subject: [PATCH 3.8 144/152] powerpc/pseries: Duplicate dtl entries sometimes sent to userspace Date: Fri, 6 Dec 2013 15:11:08 -0800 Message-Id: <1386371476-2477-145-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1386371476-2477-1-git-send-email-kamal@canonical.com> References: <1386371476-2477-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.14 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Anton Blanchard commit 84b073868b9d9e754ae48b828337633d1b386482 upstream. When reading from the dispatch trace log (dtl) userspace interface, I sometimes see duplicate entries. One example: 00000000 07 04 00 0c 00 00 48 44 00 00 00 00 00 00 00 00 00000010 00 0c a0 b4 16 83 6d 68 00 00 00 00 00 00 00 00 00000020 00 00 00 00 10 00 13 50 80 00 00 00 00 00 d0 32 00000030 07 04 00 0c 00 00 48 44 00 00 00 00 00 00 00 00 00000040 00 0c a0 b4 16 83 6d 68 00 00 00 00 00 00 00 00 00000050 00 00 00 00 10 00 13 50 80 00 00 00 00 00 d0 32 The problem is in scan_dispatch_log() where we call dtl_consumer() but bail out before incrementing the index. To fix this I moved dtl_consumer() after the timebase comparison. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt [ kamal: backport to 3.8 (context) ] Signed-off-by: Kamal Mostafa --- arch/powerpc/kernel/time.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 127361e..b89c2ee 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -213,8 +213,6 @@ static u64 scan_dispatch_log(u64 stop_tb) if (i == vpa->dtl_idx) return 0; while (i < vpa->dtl_idx) { - if (dtl_consumer) - dtl_consumer(dtl, i); dtb = dtl->timebase; tb_delta = dtl->enqueue_to_dispatch_time + dtl->ready_to_enqueue_time; @@ -227,6 +225,8 @@ static u64 scan_dispatch_log(u64 stop_tb) } if (dtb > stop_tb) break; + if (dtl_consumer) + dtl_consumer(dtl, i); stolen += tb_delta; ++i; ++dtl; -- 1.8.3.2