Re: [PATCH] bcm47xx: fix build regression

[Arend van Spriel]

On 31-05-17 18:31, Paul E. McKenney wrote:
> On Wed, May 31, 2017 at 03:34:57PM +0200, Arnd Bergmann wrote:
>> On Wed, May 31, 2017 at 3:12 PM, Paul E. McKenney
>> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>>> On Wed, May 31, 2017 at 12:21:10PM +0200, Arnd Bergmann wrote:
>>>> On Wed, May 31, 2017 at 11:43 AM, Arend van Spriel
>>>> <arend.vanspriel@xxxxxxxxxxxx> wrote:
>>>>> On 5/30/2017 1:20 PM, Arnd Bergmann wrote:
>>>>>>
>>>>>> An unknown change in the kernel headers caused a build regression
>>>>>> in an MTD partition driver:
>>>>>>
>>>>>> In file included from drivers/mtd/bcm47xxpart.c:12:0:
>>>>>> include/linux/bcm47xx_nvram.h: In function 'bcm47xx_nvram_init_from_mem':
>>>>>> include/linux/bcm47xx_nvram.h:27:10: error: 'ENOTSUPP' undeclared (first
>>>>>> use in this function)
>>>>>>
>>>>>> Clearly we want to include linux/errno.h here.
>>>>>
>>>>>
>>>>> unfortunate that you did not find the commit that caused this build
>>>>> regression. You could produce preprocessor output when it was working to see
>>>>> where errno.h got implicitly included and start looking there for git
>>>>> history.
>>>>
>>>> I did a 'git bisect run make drivers/mtd/bcm47xxpart.o' now, which pointed to
>>>> 0bc2d534708b ("rcu: Refactor #includes from include/linux/rcupdate.h").
>>>>
>>>> That commit seems reasonable, it was just bad luck that it caused this
>>>> regression. The commit is currently in the rcu/rcu/next branch of tip.git,
>>>> so Paul could merge the patch there.

Arnd,

Thanks for digging a bit further. I am a sucker for telling the whole story.

>>>
>>> Apologies for the inconvenience, not sure why 0day test robot didn't
>>> find this.  Probably because it cannot test each and every driver.  ;-)
>>
>> No worries.
>>
>>> This patch, correct?
>>>
>>>         https://lkml.org/lkml/2017/5/30/348
>>
>> Right, I should have included the link.
> 
> And my turn to say "no worries".  ;-)
> 
> I reworked the commit log to tell the full story as shown below.
> Anything I misstated or otherwise missed?

Maybe add the 'Fixes:' tag, ie.:

Fixes: 0bc2d534708b ("rcu: Refactor #includes from
include/linux/rcupdate.h")

Seems a bit redundant given that you mentioned it in the commit message,
but it might be looked for in kernel-stats scripts.

Regards,
Arend

> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit ff278071dce9af9da2b5e2b33f682710a855d266
> Author: Arnd Bergmann <arnd@xxxxxxxx>
> Date:   Wed May 31 09:26:07 2017 -0700
> 
>     bcm47xx: fix build regression
>     
>     Commit 0bc2d534708b ("rcu: Refactor #includes from include/linux/rcupdate.h")
>     caused a build regression in an MTD partition driver:
>     
>     In file included from drivers/mtd/bcm47xxpart.c:12:0:
>     include/linux/bcm47xx_nvram.h: In function 'bcm47xx_nvram_init_from_mem':
>     include/linux/bcm47xx_nvram.h:27:10: error: 'ENOTSUPP' undeclared (first use in this function)
>     
>     The rcupdate.h file has no particular need for linux/errno.h, so this
>     commit includes linux/errno.h into bcm47xx_nvram.h.
>     
>     Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>     Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> 
> diff --git a/include/linux/bcm47xx_nvram.h b/include/linux/bcm47xx_nvram.h
> index 2793652fbf66..a414a2b53e41 100644
> --- a/include/linux/bcm47xx_nvram.h
> +++ b/include/linux/bcm47xx_nvram.h
> @@ -8,6 +8,7 @@
>  #ifndef __BCM47XX_NVRAM_H
>  #define __BCM47XX_NVRAM_H
>  
> +#include <linux/errno.h>
>  #include <linux/types.h>
>  #include <linux/kernel.h>
>  #include <linux/vmalloc.h>
>