Re: [PATCH] bcm47xx: fix build regression

[Paul E. McKenney]

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.
> >
> > 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?

							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>