From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756359Ab2CGL5q (ORCPT ); Wed, 7 Mar 2012 06:57:46 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:47518 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753734Ab2CGL5o (ORCPT ); Wed, 7 Mar 2012 06:57:44 -0500 Date: Wed, 7 Mar 2012 14:57:36 +0300 From: Dan Carpenter To: Len Brown Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [patch] acpi throttling: fix endian bug in acpi_read_throttling_status() Message-ID: <20120307115736.GB13204@elgon.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A090203.4F574D36.0141,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using a u64 here creates an endian bug. We store a u32 number in the top byte which is a larger number than intended on big endian systems. There is no reason to use a 64 bit data type here, I guess it was just an oversight. I removed the initialization to zero as well. It's needed with a u64 but with a u32, the variable gets initialized properly inside the call to acpi_os_read_port(). Signed-off-by: Dan Carpenter diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c index 605a295..1d02b7b 100644 --- a/drivers/acpi/processor_throttling.c +++ b/drivers/acpi/processor_throttling.c @@ -769,7 +769,7 @@ static int acpi_read_throttling_status(struct acpi_processor *pr, u64 *value) { u32 bit_width, bit_offset; - u64 ptc_value; + u32 ptc_value; u64 ptc_mask; struct acpi_processor_throttling *throttling; int ret = -1; @@ -777,12 +777,11 @@ static int acpi_read_throttling_status(struct acpi_processor *pr, throttling = &pr->throttling; switch (throttling->status_register.space_id) { case ACPI_ADR_SPACE_SYSTEM_IO: - ptc_value = 0; bit_width = throttling->status_register.bit_width; bit_offset = throttling->status_register.bit_offset; acpi_os_read_port((acpi_io_address) throttling->status_register. - address, (u32 *) &ptc_value, + address, &ptc_value, (u32) (bit_width + bit_offset)); ptc_mask = (1 << bit_width) - 1; *value = (u64) ((ptc_value >> bit_offset) & ptc_mask);