From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753116AbaIWCey (ORCPT ); Mon, 22 Sep 2014 22:34:54 -0400 Received: from mail.kernel.org ([198.145.19.201]:37517 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753013AbaIWCev (ORCPT ); Mon, 22 Sep 2014 22:34:51 -0400 From: Zefan Li To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Aaro Koskinen , James Hogan , Zefan Li Subject: [PATCH 3.4 07/45] MIPS: OCTEON: make get_system_type() thread-safe Date: Tue, 23 Sep 2014 10:31:09 +0800 Message-Id: <1411439507-30391-7-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1411439259-30224-1-git-send-email-lizf@kernel.org> References: <1411439259-30224-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Aaro Koskinen 3.4.104-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 608308682addfdc7b8e2aee88f0e028331d88e4d upstream. get_system_type() is not thread-safe on OCTEON. It uses static data, also more dangerous issue is that it's calling cvmx_fuse_read_byte() every time without any synchronization. Currently it's possible to get processes stuck looping forever in kernel simply by launching multiple readers of /proc/cpuinfo: (while true; do cat /proc/cpuinfo > /dev/null; done) & (while true; do cat /proc/cpuinfo > /dev/null; done) & ... Fix by initializing the system type string only once during the early boot. Signed-off-by: Aaro Koskinen Reviewed-by: Markos Chandras Patchwork: http://patchwork.linux-mips.org/patch/7437/ Signed-off-by: James Hogan [lizf: Backport to 3.x: adjust context] Signed-off-by: Zefan Li --- arch/mips/cavium-octeon/setup.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c index d3a9f012..b6fb650 100644 --- a/arch/mips/cavium-octeon/setup.c +++ b/arch/mips/cavium-octeon/setup.c @@ -265,6 +265,18 @@ static irqreturn_t octeon_rlm_interrupt(int cpl, void *dev_id) } #endif +static char __read_mostly octeon_system_type[80]; + +static int __init init_octeon_system_type(void) +{ + snprintf(octeon_system_type, sizeof(octeon_system_type), "%s (%s)", + cvmx_board_type_to_string(octeon_bootinfo->board_type), + octeon_model_get_string(read_c0_prid())); + + return 0; +} +early_initcall(init_octeon_system_type); + /** * Return a string representing the system type * @@ -272,11 +284,7 @@ static irqreturn_t octeon_rlm_interrupt(int cpl, void *dev_id) */ const char *octeon_board_type_string(void) { - static char name[80]; - sprintf(name, "%s (%s)", - cvmx_board_type_to_string(octeon_bootinfo->board_type), - octeon_model_get_string(read_c0_prid())); - return name; + return octeon_system_type; } const char *get_system_type(void) -- 1.7.9.5