linux-kernel - Re: [PATCH 2/2] staging: vchiq_arm: add prototype of function vchiq_platform

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Date:   Fri, 4 Mar 2022 16:30:15 -0300
From:   Gaston Gonzalez <gascoar@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     linux-staging@...ts.linux.dev, gregkh@...uxfoundation.org,
        nsaenz@...nel.org, stefan.wahren@...e.com, ojaswin98@...il.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, gascoar@...il.com
Subject: Re: [PATCH 2/2] staging: vchiq_arm: add prototype of function
 vchiq_platform_init()

On Thu, Mar 03, 2022 at 03:25:47PM +0300, Dan Carpenter wrote:
> On Wed, Mar 02, 2022 at 06:36:38PM -0300, Gaston Gonzalez wrote:
> > Fix "no previous prototype" W=1 warning by adding the prototype of the
> > function vchiq_platform_init().
> > 
> > Note: vchiq_platform_init() is only called once in vchiq_probe(), so
> > presumably should be static function. However, making the function
> > static breaks the build.
> > 
> 
> That's weird.  I don't have an ARM cross compile set up.  How does the
> build break?
> 
> regards,
> dan carpenter
>

Hi Dan,

Test building the driver in x86 I get the error pasted below.

However, now that you mention it, I made an ARM (64 bit) cross
compilation: making the function static builds OK without the warning.
I'll to do the same for a 32 bit setup.

So I suppose that making the function static is the right approach ?

FWIW, branch and cross-compiler:

- Remote: https://github.com/raspberrypi/linux.git
- Branch: rpi-5.17.y
- gcc: aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110


-> x86 build error:

CC [M]  drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.o
In function ‘free_pagelist’,
    inlined from ‘vchiq_complete_bulk’ at drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:650:3:
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:434:4: error: argument 2 null where non-null expected [-Werror=nonnull]
  434 |    memcpy((char *)kmap(pages[0]) +
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  435 |     pagelist->offset,
      |     ~~~~~~~~~~~~~~~~~
  436 |     fragments,
      |     ~~~~~~~~~~
  437 |     head_bytes);
      |     ~~~~~~~~~~~
In file included from ./arch/x86/include/asm/string.h:5,
                 from ./include/linux/string.h:20,
                 from ./include/linux/bitmap.h:11,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/cpumask.h:5,
                 from ./arch/x86/include/asm/msr.h:11,
                 from ./arch/x86/include/asm/processor.h:22,
                 from ./arch/x86/include/asm/timex.h:5,
                 from ./include/linux/timex.h:65,
                 from ./include/linux/time32.h:13,
                 from ./include/linux/time.h:60,
                 from ./include/linux/stat.h:19,
                 from ./include/linux/module.h:13,
                 from drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:8:
drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c: In function ‘vchiq_complete_bulk’:
./arch/x86/include/asm/string_64.h:14:14: note: in a call to function ‘memcpy’ declared here
   14 | extern void *memcpy(void *to, const void *from, size_t len);
      |              ^~~~~~
cc1: all warnings being treated as errors
make[1]: *** [scripts/Makefile.build:288: drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.o] Error 1
make: *** [Makefile:1831: drivers/staging/vc04_services] Error 2

regards,

Gaston