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From: Ingo Molnar <mingo@elte.hu>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
	jkenisto@us.ibm.com, a.p.zijlstra@chello.nl, ananth@in.ibm.com,
	anton@redhat.com, masami.hiramatsu.pt@hitachi.com,
	acme@infradead.org, oleg@redhat.com, tglx@linutronix.de,
	Benjamin Herrenschmidt <benh@au1.ibm.com>,
	Josh Stone <jistone@redhat.com>,
	linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/uprobes] uprobes/core: Clean up,  refactor and improve the code
Date: Mon, 20 Feb 2012 08:38:23 +0100	[thread overview]
Message-ID: <20120220073823.GA30810@elte.hu> (raw)
In-Reply-To: <20120220060825.GA22680@linux.vnet.ibm.com>


* Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:

> The volatiles were added to arch/x86/kernel/kprobes.c because 
> of commit 7115e3fcf45 and 315eb8a2a1b. The volatiles are 
> required because gcc 4.6 gave a warning about the asm operand 
> for test_bit.  So the same were added to 
> arch/x86/kernel/uprobes.c.

Seems like a GCC bug - a bogus warning - or does it generate bad 
code as well?

In any case, kprobes.c did it correctly, it added the volatile 
*and a comment*, pointing out that it's a GCC bug. No such 
warning was added to uprobes.c, making the volatile look 
entirely spurious.

So feel free to re-add the volatile in a followup patch, just 
make sure the GCC workaround nature is documented.

Thanks,

	Ingo

  reply	other threads:[~2012-02-20  7:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-17  9:59 [tip:perf/uprobes] uprobes/core: Clean up, refactor and improve the code tip-bot for Ingo Molnar
2012-02-17 10:49 ` Ingo Molnar
2012-02-20  9:25   ` Srikar Dronamraju
2012-02-20 10:50     ` Ingo Molnar
2012-02-20  6:08 ` Srikar Dronamraju
2012-02-20  7:38   ` Ingo Molnar [this message]
2012-02-20 10:13     ` Srikar Dronamraju
2012-02-20 10:51       ` Ingo Molnar

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