From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762594AbZFKW7n (ORCPT ); Thu, 11 Jun 2009 18:59:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760842AbZFKW71 (ORCPT ); Thu, 11 Jun 2009 18:59:27 -0400 Received: from ozlabs.org ([203.10.76.45]:37882 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760644AbZFKW70 (ORCPT ); Thu, 11 Jun 2009 18:59:26 -0400 To: linux-kernel@vger.kernel.org From: Rusty Russell Date: Thu, 11 Jun 2009 22:59:58 +0930 Subject: [PATCH 6/6] dcdbas: don't play with current's cpumask Cc: Matthew Garrett Cc: Matt Domsch Cc: Douglas_Warzecha@dell.com Message-Id: <20090611225928.31C72DDD1B@ozlabs.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's generally a very bad idea to mug some process's cpumask: it could legitimately and reasonably be changed by root, which could break us (if done before our code) or them (if we restore the wrong value). So we use smp_call_function_single instead of cpumask games. I hope we are allowed to trigger the smi from interrupt context. Signed-off-by: Rusty Russell Cc: Matthew Garrett Cc: Matt Domsch Cc: Douglas_Warzecha@dell.com --- drivers/firmware/dcdbas.c | 51 +++++++++++++++++----------------------------- 1 file changed, 19 insertions(+), 32 deletions(-) diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c --- a/drivers/firmware/dcdbas.c +++ b/drivers/firmware/dcdbas.c @@ -237,34 +237,9 @@ static ssize_t host_control_on_shutdown_ return count; } -/** - * dcdbas_smi_request: generate SMI request - * - * Called with smi_data_lock. - */ -int dcdbas_smi_request(struct smi_cmd *smi_cmd) +static void generate_smi(void *_smi_cmd) { - cpumask_var_t old_mask; - int ret = 0; - - if (smi_cmd->magic != SMI_CMD_MAGIC) { - dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n", - __func__); - return -EBADR; - } - - /* SMI requires CPU 0 */ - if (!alloc_cpumask_var(&old_mask, GFP_KERNEL)) - return -ENOMEM; - - cpumask_copy(old_mask, ¤t->cpus_allowed); - set_cpus_allowed_ptr(current, cpumask_of(0)); - if (smp_processor_id() != 0) { - dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n", - __func__); - ret = -EBUSY; - goto out; - } + struct smi_cmd *smi_cmd = _smi_cmd; /* generate SMI */ asm volatile ( @@ -276,14 +251,26 @@ int dcdbas_smi_request(struct smi_cmd *s "c" (smi_cmd->ecx) : "memory" ); - -out: - set_cpus_allowed_ptr(current, old_mask); - free_cpumask_var(old_mask); - return ret; } /** + * dcdbas_smi_request: generate SMI request + * + * Called with smi_data_lock. + */ +int dcdbas_smi_request(struct smi_cmd *smi_cmd) +{ + if (smi_cmd->magic != SMI_CMD_MAGIC) { + dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n", + __func__); + return -EBADR; + } + + /* SMI requires CPU 0 */ + smp_call_function_single(0, generate_smi, smi_cmd, 1); + return 0; +} +/** * smi_request_store: * * The valid values are: