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Date: Fri, 18 Jan 2008 13:18:07 +0800
From: WANG Cong <xiyou.wangcong@gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/2] Make kthread_create and kthread_run typesafe
Message-ID: <20080118051807.GB2559@hacking>
Reply-To: WANG Cong <xiyou.wangcong@gmail.com>
References: <200801181151.40141.rusty@rustcorp.com.au>
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On Fri, Jan 18, 2008 at 11:51:39AM +1100, Rusty Russell wrote:
>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.

{snip}

>+#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[], ...);

Rusty, excellent work!!

I really like this. It is a good trick, neat and clean.
Thanks.