Re: [PATCH 02/02] clk: clk-of: Use alloc_bootmem() instead of kzalloc()

From: Paul Mundt <lethal@linux-sh.org>
To: Chris Ball <cjb@laptop.org>
Cc: Rob Herring <robherring2@gmail.com>,
	Mitch Bradley <wmb@laptop.org>,
	mturquette@linaro.org, devicetree-discuss@lists.ozlabs.org,
	sboyd@codeaurora.org, linux-kernel@vger.kernel.org,
	Rob Herring <rob.herring@calxeda.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	skannan@codeaurora.org, shawn.guo@linaro.org,
	s.hauer@pengutronix.de, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 02/02] clk: clk-of: Use alloc_bootmem() instead of kzalloc()
Date: Thu, 21 Jun 2012 21:18:44 +0900	[thread overview]
Message-ID: <20120621121843.GA20236@linux-sh.org> (raw)
In-Reply-To: <87395p15or.fsf_-_@octavius.laptop.org>

On Thu, Jun 21, 2012 at 03:32:04AM -0400, Chris Ball wrote:
> When of_clk_add_provider() is used at boot time (during .init_early on
> ARM, in the motivating case for this patch), kzalloc() cannot be used
> because slab isn't up yet.
> 
> Signed-off-by: Chris Ball <cjb@laptop.org>

I wouldn't use alloc_bootmem() unconditionally for this, as you have no
idea where other platforms may wire the call site up. slab is also
available a lot earlier now than it used to be, so many places that
required bootmem pages previously can get away with slab allocations now.

You could rework this as:

	if (slab_is_available())
		cp = kzalloc(...)
	else
		cp = alloc_bootmem(...)

and then it doesn't matter when and where it gets called.