linux-kernel - Re: [PATCH] firmware: Don't attempt to allocate zero bytes with vmalloc()

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Message-ID: <20121009071343.GW8237@opensource.wolfsonmicro.com>
Date:	Tue, 9 Oct 2012 16:13:45 +0900
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] firmware: Don't attempt to allocate zero bytes with
 vmalloc()

On Tue, Oct 09, 2012 at 03:05:30PM +0800, Ming Lei wrote:
> On Tue, Oct 9, 2012 at 12:19 PM, Mark Brown

> > It seems better to punt that decision to callers - for example, the case

> In fact, -ENOENT is returned to caller for non-direct loading situation,
> see_request_firmware_load().

> I understand drivers(caller) may be cheated if a zero-length firmware
> image is obtained. In normal situation, one firmware image should
> include something, instead of nothing, :-)

Hrm, that didn't seem to be happening for me - the firmware load
completed successfully.  Have to check how that happened.

> > I ran into this with was a driver that was using a zero length firmware
> > to say that it didn't want to load an optional image but also didn't
> > want to have to time out if that was the case.  That doesn't seem

> If so, I am wondering why the driver has to call request_firmware()?
> Looks just bypassing request_firmware() is fine for the driver, doesn't it?

A driver has no way to tell if the firmware is there or not without
asking for it.
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