From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164589AbdD1Fac (ORCPT ); Fri, 28 Apr 2017 01:30:32 -0400 Received: from mga03.intel.com ([134.134.136.65]:36155 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1164568AbdD1Fa1 (ORCPT ); Fri, 28 Apr 2017 01:30:27 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.37,387,1488873600"; d="scan'208";a="95168977" From: Lv Zheng To: "Rafael J . Wysocki" , "Rafael J . Wysocki" , Len Brown Cc: Lv Zheng , Lv Zheng , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Dan Williams Subject: [PATCH v3 2/4] ACPICA: Tables: Add mechanism to allow to balance late stage acpi_get_table() independently Date: Fri, 28 Apr 2017 13:30:20 +0800 Message-Id: <89693a14ceb97e3d1fa7cc098b15c73f5b176863.1493357251.git.lv.zheng@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <5361b51c7c257b3216475018a3a5cc4f8b6b21c6.1493281247.git.lv.zheng@intel.com> References: <5361b51c7c257b3216475018a3a5cc4f8b6b21c6.1493281247.git.lv.zheng@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For all frequent late stage acpi_get_table() clone invocations, we should only fix them altogether, otherwise, excessive acpi_put_table() could unexpectedly unmap the table used by the other users. Thus the current plan is to fix all acpi_get_table() clones together or to fix none of them. This prevents kernel developers from improving the late stage code quality without waiting for the ACPICA upstream to improve first. This patch adds a mechanism to stop decrementing validation count to prevent the table unmapping operations so that acpi_put_table() balance fixes can be done independently to each others. Cc: Dan Williams Signed-off-by: Lv Zheng --- drivers/acpi/acpica/tbutils.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/acpica/tbutils.c b/drivers/acpi/acpica/tbutils.c index 7abe665..b517bd0 100644 --- a/drivers/acpi/acpica/tbutils.c +++ b/drivers/acpi/acpica/tbutils.c @@ -445,12 +445,18 @@ void acpi_tb_put_table(struct acpi_table_desc *table_desc) ACPI_FUNCTION_TRACE(acpi_tb_put_table); - if (table_desc->validation_count == 0) { + if ((table_desc->validation_count + 1) == 0) { ACPI_WARNING((AE_INFO, - "Table %p, Validation count is zero before decrement\n", + "Table %p, Validation count is about to expire, decrement is unsafe\n", table_desc)); return_VOID; } + if (table_desc->validation_count == 0) { + ACPI_ERROR((AE_INFO, + "Table %p, Validation count is zero before decrement\n", + table_desc)); + return_VOID; + } table_desc->validation_count--; if (table_desc->validation_count == 0) { -- 2.7.4