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Date: Fri, 3 Apr 2009 15:16:29 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] tracing: fix splice return too large
Message-ID: <20090403131629.GA8875@elte.hu>
References: <49D46674.9030804@cn.fujitsu.com>
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* Lai Jiangshan <laijs@cn.fujitsu.com> wrote:

> -	for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
> +	if (*ppos & (PAGE_SIZE - 1)) {
> +		WARN_ONCE(1, "Ftrace: previous read must page-align\n");
> +		return -EINVAL;
> +	}
> +
> +	if (len & (PAGE_SIZE - 1)) {
> +		WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
> +		if (len < PAGE_SIZE)
> +			return -EINVAL;
> +		len &= PAGE_MASK;
> +	}

Hm, the fix looks good, but is it a good idea to allow the 
triggering of this message from user-space?

	Ingo