linux-kernel - Re: [PATCH v2 30/30] misc: cxl: flash: Remove unused pointer

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Message-ID: <20200701133123.GF1179328@dell>
Date:   Wed, 1 Jul 2020 14:31:23 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2 30/30] misc: cxl: flash: Remove unused pointer

On Wed, 01 Jul 2020, Greg KH wrote:

> On Wed, Jul 01, 2020 at 09:31:18AM +0100, Lee Jones wrote:
> > The DRC index pointer us updated on an OPCODE_ADD, but never
> > actually read.  Remove the used pointer and shift up OPCODE_ADD
> > to group with OPCODE_DELETE which also provides a noop.
> > 
> > Fixes the following W=1 kernel build warning:
> > 
> >  drivers/misc/cxl/flash.c: In function ‘update_devicetree’:
> >  drivers/misc/cxl/flash.c:178:16: warning: variable ‘drc_index’ set but not used [-Wunused-but-set-variable]
> >  178 | __be32 *data, drc_index, phandle;
> >  | ^~~~~~~~~
> > 
> > Cc: Frederic Barrat <fbarrat@...ux.ibm.com>
> > Cc: Andrew Donnellan <ajd@...ux.ibm.com>
> > Cc: linuxppc-dev@...ts.ozlabs.org
> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > ---
> >  drivers/misc/cxl/flash.c | 7 ++-----
> >  1 file changed, 2 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/misc/cxl/flash.c b/drivers/misc/cxl/flash.c
> > index cb9cca35a2263..24e3dfcc91a74 100644
> > --- a/drivers/misc/cxl/flash.c
> > +++ b/drivers/misc/cxl/flash.c
> > @@ -175,7 +175,7 @@ static int update_devicetree(struct cxl *adapter, s32 scope)
> >  	struct update_nodes_workarea *unwa;
> >  	u32 action, node_count;
> >  	int token, rc, i;
> > -	__be32 *data, drc_index, phandle;
> > +	__be32 *data, phandle;
> >  	char *buf;
> >  
> >  	token = rtas_token("ibm,update-nodes");
> > @@ -206,15 +206,12 @@ static int update_devicetree(struct cxl *adapter, s32 scope)
> >  
> >  				switch (action) {
> >  				case OPCODE_DELETE:
> > +				case OPCODE_ADD:
> >  					/* nothing to do */
> >  					break;
> >  				case OPCODE_UPDATE:
> >  					update_node(phandle, scope);
> >  					break;
> > -				case OPCODE_ADD:
> > -					/* nothing to do, just move pointer */
> > -					drc_index = *data++;
> > -					break;
> 
> I think this is not correct, as *data++ changes the value there, and so
> this changes the logic of the code.

Great spot.

Looks like I overlooked that the pointer itself is being incremented.

> Dropping this one from my queue.

Sounds good.

I'll fix-up and send this separately at a later date.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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