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Date: Tue, 26 May 2009 02:02:32 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>, Jens Axboe <jens.axboe@oracle.com>,
       Steven Rostedt <rostedt@goodmis.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Tom Zanussi <tzanussi@gmail.com>, "Theodore Ts'o" <tytso@mit.edu>,
       Steven Whitehouse <swhiteho@redhat.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Jeff Moyer <jmoyer@redhat.com>, Christoph Hellwig <hch@infradead.org>,
       FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] tracing/events: make __string() more general
Message-ID: <20090526060232.GA10669@infradead.org>
References: <4A1B6A2F.2040703@cn.fujitsu.com> <4A1B6A4C.3070407@cn.fujitsu.com>
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On Tue, May 26, 2009 at 12:04:28PM +0800, Li Zefan wrote:
> This changes __string(..., src) to __string(..., len), thus makes it more
> general, and then block TRACE_EVENT() can use it.
> 
> Also introduce __fetch_str(), which is used in TP_assign() and returns
> the address of the string, while __get_str() is used in TP_print().

If you want to make it really generaly dealing with NULL string pointers
would be extremly helpful.  I ran into that limitation (and the length
one fixed here) when converting the XFS tracing over.