linux-kernel - Re: trace_printk is doing weird things with my arguments

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Date:	Mon, 12 Dec 2011 15:44:59 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Josef Bacik <josef@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: trace_printk is doing weird things with my arguments

On Mon, 2011-12-12 at 15:32 -0500, Josef Bacik wrote:
> 
> That worked perfectly.  So will I have this problem when I got to turn these
> things into tracepoints or will those work out right?  Thanks,

The TP_fast_assign() is exactly how things are copied into the ring
buffer. If you have all the necessary data copied then, and don't
dereference it in TP_printk(), then you are fine.

IOW,

	TP_fast_assign( entry->id = ptr->id),
	TP_printk ("id: %lx", entry->id)

will work, but

	TP_fast_assign(entry->ptr = ptr),
	TP_printk("id: %lx", entry->ptr->id)

will not.


-- Steve


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