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Date: Wed, 26 Aug 2009 14:41:16 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Peter Zijlstra <peterz@infradead.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Hendrik Brueckner <brueckner@linux.vnet.ibm.com>,
       Jason Baron <jbaron@redhat.com>, linux-kernel@vger.kernel.org,
       mingo@elte.hu, laijs@cn.fujitsu.com, rostedt@goodmis.org,
       jiayingz@google.com, mbligh@google.com, lizf@cn.fujitsu.com,
       Heiko Carstens <heiko.carstens@de.ibm.com>,
       Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH 08/12] add trace events for each syscall entry/exit
Message-ID: <20090826184116.GA20283@infradead.org>
References: <20090825141547.GE6114@nowhere> <20090825160237.GG4639@cetus.boeblingen.de.ibm.com> <20090825162004.GA25058@Krystal> <20090825165912.GI6114@nowhere> <20090825173107.GJ6114@nowhere> <20090825183119.GC2448@Krystal> <1251267669.7538.1195.camel@twins> <20090826170812.GC21456@Krystal>
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On Wed, Aug 26, 2009 at 01:08:12PM -0400, Mathieu Desnoyers wrote:
> Nah. And I start to feel comfortable with syscall entry/exit being only
> be traced for userspace threads. But as I pointed out in a follow-up
> email, the lack of sys_*() tracing for invocation from within the kernel
> might be problematic. This is actually my main point.

We do not support system calls from kernelspace anymore.  All the
macros to do real system calls are gone, and there are very very few
places left calling sys_foo as normal function calls.

An how exactly is calling sys_foo as a normal function call different
from calling do_foo or vfs_foo?