From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752565AbZDMAGl (ORCPT ); Sun, 12 Apr 2009 20:06:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751955AbZDMAGa (ORCPT ); Sun, 12 Apr 2009 20:06:30 -0400 Received: from ozlabs.org ([203.10.76.45]:39041 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750758AbZDMAG3 (ORCPT ); Sun, 12 Apr 2009 20:06:29 -0400 To: linux-kernel@vger.kernel.org From: Rusty Russell Date: Mon, 13 Apr 2009 09:30:03 +0930 Subject: [PATCH 7/7] work_on_cpu: use on drivers/firmware/dcdbas.c Cc: Matthew Garrett Cc: Matt Domsch Cc: Douglas_Warzecha@dell.com Message-Id: <20090413000628.29833DE108@ozlabs.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Impact: don't play with current's cpumask 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 work_on_cpu instead of cpumask games. Note one subtle change. If we can't get to CPU 0 for some reason, the return will be -EINVAL not -EBUSY. We could fix this in the caller? ie: return work_on_cpu(0, generate_smi, smi_cmd) == 0 ? 0 : -EBUSY; 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 long 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 ( @@ -276,13 +251,25 @@ 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; + return 0; } +/** + * 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 */ + return work_on_cpu(0, generate_smi, smi_cmd); +} /** * smi_request_store: *