Subject: linux-next: build failure after merge of the tip tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 31 Jul 2020 15:53:04 +1000

Hi all,

After merging the tip tree, today's linux-next build (arm
multi_v7_defconfig) failed like this:

In file included from include/asm-generic/getorder.h:8,
                 from arch/arm/include/asm/page.h:166,
                 from arch/arm/include/asm/thread_info.h:14,
                 from arch/arm/include/asm/percpu.h:16,
                 from include/linux/irqflags.h:17,
                 from arch/arm/include/asm/bitops.h:28,
                 from include/linux/bitops.h:29,
                 from include/linux/kernel.h:12,
                 from include/asm-generic/bug.h:20,
                 from arch/arm/include/asm/bug.h:60,
                 from include/linux/bug.h:5,
                 from include/linux/page-flags.h:10,
                 from kernel/bounds.c:10:
include/linux/log2.h: In function '__ilog2_u32':
include/linux/log2.h:24:9: error: implicit declaration of function 'fls' [-Werror=implicit-function-declaration]
   24 |  return fls(n) - 1;
      |         ^~~

And so on ...

Caused by commit

  a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")

interacting with commit

  00a30a5c9e6b ("arm: include asm/thread_info.h in asm/percpu.h")

(which was a fix of mine but now the equivalent is in Linus' tree as commit

  aa54ea903abb ("ARM: percpu.h: fix build error")
)

I have reverted 00a30a5c9e6b since commit

  a6342915881a ("arm: Break cyclic percpu include")

(which precedes a21ee6055c30) acomplishes the same thing differently.
Something will be required when this is merged with Linus' tree, though.

-- 
Cheers,
Stephen Rothwell