linux-kernel - Re: [PATCH 2/4] remoteproc: Split firmware name allocation from rproc

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Date:   Mon, 13 Apr 2020 17:55:06 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Alex Elder <elder@...aro.org>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>, ohad@...ery.com,
        s-anna@...com, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] remoteproc: Split firmware name allocation from
 rproc_alloc()

On Mon 13 Apr 13:56 PDT 2020, Alex Elder wrote:

> On 4/13/20 2:33 PM, Mathieu Poirier wrote:
> > Make the firmware name allocation a function on its own in order to
> > introduce more flexibility to function rproc_alloc().
> > 
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> 
> I didn't look at the larger context (MCU series); I'm only looking
> at this (and the others in this series) in isolation.  I like
> that you're encapsulating this stuff into functions but doing so
> doesn't really add any flexibility.
> 
> Two small suggestions for you to consider but they're truly
> more about style so it's entirely up to you.  Outside of that
> this looks straightforward to me, and the result of the series
> is an improvement.
> 
> I'll let you comment on my suggestions before offering my
> "reviewed-by" indication.
> 
> 					-Alex
> 
> > ---
> >  drivers/remoteproc/remoteproc_core.c | 66 ++++++++++++++++------------
> >  1 file changed, 39 insertions(+), 27 deletions(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> > index 80056513ae71..4dee63f319ba 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -1979,6 +1979,33 @@ static const struct device_type rproc_type = {
> >  	.release	= rproc_type_release,
> >  };
> >  
> > +static int rproc_alloc_firmware(struct rproc *rproc,
> > +				const char *name, const char *firmware)
> > +{
> > +	char *p, *template = "rproc-%s-fw";
> > +	int name_len;
> 
> Not a big deal (and maybe it's not consistent with other nearby
> style) but template and name_len could be defined inside the
> "if (!firmware)" block.
> 

I prefer variables declared in the beginning of the function, so I'm
happy with this.

> > +	if (!firmware) {
> > +		/*
> > +		 * If the caller didn't pass in a firmware name then
> > +		 * construct a default name.
> > +		 */
> > +		name_len = strlen(name) + strlen(template) - 2 + 1;
> > +		p = kmalloc(name_len, GFP_KERNEL);
> 
> 
> I don't know if it would be an improvement, but you could
> check for a null p value below for both cases.  I.e.:
> 
> 		if (p)
> 			snprintf(p, ...);
> 

Moving the common NULL check and return out seems nice, but given that
we then have to have this positive conditional I think the end result is
more complex.

That said, if we're not just doing a verbatim copy from rproc_alloc() I
think we should make this function:

	if (!firmware)
		p = kasprintf(GFP_KERNEL, "rproc-%s-fw", name);
	else
		p = kstrdup_const(firmware, GFP_KERNEL);

	rproc->firmware = p;

	return p ? 0 : -ENOMEM;

Regards,
Bjorn

> (more below)
> 
> > +		if (!p)
> > +			return -ENOMEM;
> > +		snprintf(p, name_len, template, name);
> > +	} else {
> > +		p = kstrdup(firmware, GFP_KERNEL);
> > +		if (!p)
> > +			return -ENOMEM;
> > +	}
> > +
> 
> 	if (!p)
> 		return -ENOMEM;
> 	
> > +	rproc->firmware = p;
> > +
> > +	return 0;
> > +}
> > +
> >  /**
> >   * rproc_alloc() - allocate a remote processor handle
> >   * @dev: the underlying device
> > @@ -2007,42 +2034,21 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
> >  			  const char *firmware, int len)
> >  {
> >  	struct rproc *rproc;
> > -	char *p, *template = "rproc-%s-fw";
> > -	int name_len;
> >  
> >  	if (!dev || !name || !ops)
> >  		return NULL;
> >  
> > -	if (!firmware) {
> > -		/*
> > -		 * If the caller didn't pass in a firmware name then
> > -		 * construct a default name.
> > -		 */
> > -		name_len = strlen(name) + strlen(template) - 2 + 1;
> > -		p = kmalloc(name_len, GFP_KERNEL);
> > -		if (!p)
> > -			return NULL;
> > -		snprintf(p, name_len, template, name);
> > -	} else {
> > -		p = kstrdup(firmware, GFP_KERNEL);
> > -		if (!p)
> > -			return NULL;
> > -	}
> > -
> >  	rproc = kzalloc(sizeof(struct rproc) + len, GFP_KERNEL);
> > -	if (!rproc) {
> > -		kfree(p);
> > +	if (!rproc)
> >  		return NULL;
> > -	}
> > +
> > +	if (rproc_alloc_firmware(rproc, name, firmware))
> > +		goto free_rproc;
> >  
> >  	rproc->ops = kmemdup(ops, sizeof(*ops), GFP_KERNEL);
> > -	if (!rproc->ops) {
> > -		kfree(p);
> > -		kfree(rproc);
> > -		return NULL;
> > -	}
> > +	if (!rproc->ops)
> > +		goto free_firmware;
> >  
> > -	rproc->firmware = p;
> >  	rproc->name = name;
> >  	rproc->priv = &rproc[1];
> >  	rproc->auto_boot = true;
> > @@ -2091,6 +2097,12 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
> >  	rproc->state = RPROC_OFFLINE;
> >  
> >  	return rproc;
> > +
> > +free_firmware:
> > +	kfree(rproc->firmware);
> > +free_rproc:
> > +	kfree(rproc);
> > +	return NULL;
> >  }
> >  EXPORT_SYMBOL(rproc_alloc);
> >  
> > 
>