linux-kernel - Re: smp_call_function_single with wait=0 considered harmful

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Message-ID: <20131206105639.GA20448@infradead.org>
Date:	Fri, 6 Dec 2013 02:56:39 -0800
From:	Christoph Hellwig <hch@...radead.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tony Luck <tony.luck@...el.com>,
	Robert Richter <rric@...nel.org>,
	Aaro Koskinen <aaro.koskinen@....fi>,
	David Daney <david.daney@...ium.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: smp_call_function_single with wait=0 considered harmful

On Thu, Dec 05, 2013 at 02:43:03PM -0700, Bjorn Helgaas wrote:
> smp_call_function_single() sets "csd = &__get_cpu_var(csd_data)", so
> it's not using a struct on the stack.  We'll queue up "func" and
> likely will return before it is executed, but that should be fine
> because nobody will overwrite csd_data until it *is* executed and
> csd_unlock() has been called.

You're right, I missed the usage of the per-cpu data later in the
function.

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