Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757998AbYJWA7p (ORCPT ); Wed, 22 Oct 2008 20:59:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754146AbYJWA54 (ORCPT ); Wed, 22 Oct 2008 20:57:56 -0400 Received: from ozlabs.org ([203.10.76.45]:40318 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753660AbYJWA5w (ORCPT ); Wed, 22 Oct 2008 20:57:52 -0400 To: linux-kernel@vger.kernel.org From: Rusty Russell Date: Thu Oct 23 11:55:16 EST 2008 CC: travis@sgi.com Subject: [PATCH 1/7] work_on_cpu: helper for doing task on a CPU. Cc: Ingo Molnar Message-Id: <20081023005751.53973DDEFE@ozlabs.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2804 Lines: 102 Several places in the kernel do the following: saved_mask = current->cpus_allowed; set_cpus_allowed_ptr(current, &cpumask_of_cpu(pr->id)); somefunc(); /* restore the previous state */ set_cpus_allowed_ptr(current, &saved_mask); This is bad, because a process's cpumask is observable and manipulatable by userspace and should not be toyed with. We have the infrastructure, this just creates a nice wrapper to encourage its use. Signed-off-by: Rusty Russell Cc: Ingo Molnar --- include/linux/workqueue.h | 8 +++++++ kernel/workqueue.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+) diff -r b72e0cbdd249 include/linux/workqueue.h --- a/include/linux/workqueue.h Thu Oct 23 00:39:36 2008 +1100 +++ b/include/linux/workqueue.h Thu Oct 23 10:53:51 2008 +1100 @@ -240,4 +240,12 @@ void cancel_rearming_delayed_work(struct cancel_delayed_work_sync(work); } +#ifndef CONFIG_SMP +static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) +{ + return fn(arg); +} +#else +long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg); +#endif /* CONFIG_SMP */ #endif diff -r b72e0cbdd249 kernel/workqueue.c --- a/kernel/workqueue.c Thu Oct 23 00:39:36 2008 +1100 +++ b/kernel/workqueue.c Thu Oct 23 10:53:51 2008 +1100 @@ -970,6 +970,54 @@ undo: return ret; } +#ifdef CONFIG_SMP +struct work_for_cpu { + struct work_struct work; + long (*fn)(void *); + void *arg; + long ret; + struct completion done; +}; + +static void do_work_for_cpu(struct work_struct *w) +{ + struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work); + + wfc->ret = wfc->fn(wfc->arg); + complete(&wfc->done); +} + +/** + * work_on_cpu - run a function in user context on a particular cpu + * @cpu: the cpu to run on + * @fn: the function to run + * @arg: the function arg + * + * This will return -EINVAL in the cpu is not online, or the return value + * of @fn otherwise. + */ +long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) +{ + struct work_for_cpu wfc; + + INIT_WORK(&wfc.work, do_work_for_cpu); + init_completion(&wfc.done); + wfc.fn = fn; + wfc.arg = arg; + get_online_cpus(); + if (unlikely(!cpu_online(cpu))) { + wfc.ret = -EINVAL; + complete(&wfc.done); + } else + schedule_work_on(cpu, &wfc.work); + put_online_cpus(); + wait_for_completion(&wfc.done); + + return wfc.ret; +} +EXPORT_SYMBOL_GPL(work_on_cpu); +#endif /* CONFIG_SMP */ + void __init init_workqueues(void) { cpu_populated_map = cpu_online_map; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/