From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759480AbYARAwX (ORCPT ); Thu, 17 Jan 2008 19:52:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757220AbYARAwP (ORCPT ); Thu, 17 Jan 2008 19:52:15 -0500 Received: from ozlabs.org ([203.10.76.45]:43228 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756319AbYARAwO (ORCPT ); Thu, 17 Jan 2008 19:52:14 -0500 From: Rusty Russell To: linux-kernel@vger.kernel.org Subject: [PATCH 1/2] Make kthread_create and kthread_run typesafe Date: Fri, 18 Jan 2008 11:51:39 +1100 User-Agent: KMail/1.9.6 (enterprise 0.20070907.709405) Cc: Linus Torvalds , Andrew Morton MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200801181151.40141.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With a little macro ugliness, we can make kthread_create() and kthread_run() typesafe: avoid the casts to and from void *. To do this we use a temporary function pointer which takes the type of the data as a callback: if the function doesn't match, we get: warning: initialization from incompatible pointer type It's actually slightly over-strict, since a void * would be compatible with any function type, but there's only one such case in the kernel anyway. Signed-off-by: Rusty Russell --- include/linux/kthread.h | 30 +++++++++++++++++++++++++++--- kernel/kthread.c | 29 +++++------------------------ 2 files changed, 32 insertions(+), 27 deletions(-) diff -r 110aa94129d0 include/linux/kthread.h --- a/include/linux/kthread.h Fri Jan 18 10:32:31 2008 +1100 +++ b/include/linux/kthread.h Fri Jan 18 11:31:49 2008 +1100 @@ -4,9 +4,33 @@ #include #include -struct task_struct *kthread_create(int (*threadfn)(void *data), - void *data, - const char namefmt[], ...); +/** + * kthread_create - create a kthread. + * @threadfn: the function to run until signal_pending(current). + * @data: data ptr for @threadfn. + * @namefmt: printf-style name for the thread. + * + * Description: This helper function creates and names a kernel + * thread. The thread will be stopped: use wake_up_process() to start + * it. See also kthread_run(), kthread_create_on_cpu(). + * + * When woken, the thread will run @threadfn() with @data as its + * argument. @threadfn() can either call do_exit() directly if it is a + * standalone thread for which noone will call kthread_stop(), or + * return when 'kthread_should_stop()' is true (which means + * kthread_stop() has been called). The return value should be zero + * or a negative error number; it will be passed to kthread_stop(). + * + * Returns a task_struct or ERR_PTR(-ENOMEM). + */ +#define kthread_create(threadfn, data, namefmt...) ({ \ + int (*_threadfn)(typeof(data)) = (threadfn); \ + __kthread_create((void *)_threadfn, (data), namefmt); \ +}) + +struct task_struct *__kthread_create(int (*threadfn)(void *data), + void *data, + const char namefmt[], ...); /** * kthread_run - create and wake a thread. diff -r 110aa94129d0 kernel/kthread.c --- a/kernel/kthread.c Fri Jan 18 10:32:31 2008 +1100 +++ b/kernel/kthread.c Fri Jan 18 11:31:49 2008 +1100 @@ -102,29 +102,10 @@ static void create_kthread(struct kthrea complete(&create->done); } -/** - * kthread_create - create a kthread. - * @threadfn: the function to run until signal_pending(current). - * @data: data ptr for @threadfn. - * @namefmt: printf-style name for the thread. - * - * Description: This helper function creates and names a kernel - * thread. The thread will be stopped: use wake_up_process() to start - * it. See also kthread_run(), kthread_create_on_cpu(). - * - * When woken, the thread will run @threadfn() with @data as its - * argument. @threadfn() can either call do_exit() directly if it is a - * standalone thread for which noone will call kthread_stop(), or - * return when 'kthread_should_stop()' is true (which means - * kthread_stop() has been called). The return value should be zero - * or a negative error number; it will be passed to kthread_stop(). - * - * Returns a task_struct or ERR_PTR(-ENOMEM). - */ -struct task_struct *kthread_create(int (*threadfn)(void *data), - void *data, - const char namefmt[], - ...) +struct task_struct *__kthread_create(int (*threadfn)(void *data), + void *data, + const char namefmt[], + ...) { struct kthread_create_info create; @@ -149,7 +130,7 @@ struct task_struct *kthread_create(int ( } return create.result; } -EXPORT_SYMBOL(kthread_create); +EXPORT_SYMBOL(__kthread_create); /** * kthread_bind - bind a just-created kthread to a cpu.