linux-kernel - Re: [PATCH v2 10/23] firmware: add helper to copy built-in data to pre-alloc buffer

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Message-ID: <20171130201842.GL729@wotan.suse.de>
Date:   Thu, 30 Nov 2017 21:18:42 +0100
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>, akpm@...ux-foundation.org,
        keescook@...omium.org, mfuzzey@...keon.com,
        zohar@...ux.vnet.ibm.com, dhowells@...hat.com,
        pali.rohar@...il.com, tiwai@...e.de, arend.vanspriel@...adcom.com,
        zajec5@...il.com, nbroeking@...com, markivx@...eaurora.org,
        stephen.boyd@...aro.org, broonie@...nel.org,
        dmitry.torokhov@...il.com, dwmw2@...radead.org,
        torvalds@...ux-foundation.org, Abhay_Salunke@...l.com,
        bjorn.andersson@...aro.org, jewalt@...innovations.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 10/23] firmware: add helper to copy built-in data to
 pre-alloc buffer

On Wed, Nov 29, 2017 at 11:17:15AM +0100, Greg KH wrote:
> On Mon, Nov 20, 2017 at 10:23:56AM -0800, Luis R. Rodriguez wrote:
> > This makes it clearer that the parameters passed are only used for
> > the preallocated buffer option, ie, when a caller uses:
> > 
> > 	request_firmware_into_buf()
> > 
> > Otherwise this code won't run. We flip the logic just so the actual
> > prellocated buf code is not indented.
> > 
> > Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
> > ---
> >  drivers/base/firmware_class.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index 4f64410fe7e6..aba3f2cbe2f4 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -146,6 +146,14 @@ static struct firmware_cache fw_cache;
> >  extern struct builtin_fw __start_builtin_fw[];
> >  extern struct builtin_fw __end_builtin_fw[];
> >  
> > +static void fw_copy_to_prealloc_buf(struct firmware *fw,
> > +				    void *buf, size_t size)
> > +{
> > +	if (!buf || size < fw->size)
> > +		return;
> 
> Shouldn't this return an error?

No, its a no-op when these are not set, and its actually *why* I created
the function. The parameters are *only* useful for the prealloc buf fw
calls. Keeping track of all this while reading the code is actually not
easy and this should make it clearer.

> 
> > +	memcpy(buf, fw->data, fw->size);
> 
> I'll take this, but it feels really odd...

Thanks.

  Luis