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From: Johannes Berg <johannes@sipsolutions.net>
To: linux-kernel <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: event tracing, ringbuffer and RB_MAX_SMALL_DATA
Date: Tue, 14 Jul 2009 19:18:11 +0200	[thread overview]
Message-ID: <1247591891.7178.20.camel@johannes.local> (raw)

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Hi,

By code inspection, I think there's a bug if your event contains only

	__dynamic_array(u8, buf, buflen)

and your buflen is only, say, 3. Then the event size will be the common
event size (12 bytes) plus this, so 15, which is well below
RB_MAX_SMALL_DATA (4*28 = 112), so it'll be divided by four to be stored
into type_len. At this point, however, you've lost the information that
your dynamic array was only three bytes, and it'll be considered _four_
bytes long by parsers as far as I can tell?

johannes

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             reply	other threads:[~2009-07-14 17:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-14 17:18 Johannes Berg [this message]
2009-07-15  1:08 ` Li Zefan
2009-07-15  9:48   ` Johannes Berg
2009-07-16  0:48     ` Li Zefan
2009-07-21  1:25       ` Steven Rostedt
2009-07-21  1:30         ` Li Zefan
2009-07-21  1:42           ` Steven Rostedt

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