mainline build failure due to 8238b4579866 ("wait_on_bit: add an acquire memory barrier")

["Sudip Mukherjee (Codethink)" <sudipm.mukherjee@gmail.com>]

Hi All,

The latest mainline kernel branch fails to build alpha and s390 allmodconfig.

alpha error is:

In file included from ./include/linux/thread_info.h:27,
                 from ./include/asm-generic/current.h:5,
                 from ./arch/alpha/include/generated/asm/current.h:1,
                 from ./include/linux/sched.h:12,
                 from arch/alpha/kernel/asm-offsets.c:10:
./include/linux/wait_bit.h: In function 'wait_on_bit':
./include/asm-generic/bitops/non-instrumented-non-atomic.h:15:33: error: implicit declaration of function 'arch_test_bit_acquire'; did you mean '_test_bit_acquire'? [-Werror=implicit-function-declaration]
   15 | #define _test_bit_acquire       arch_test_bit_acquire
      |                                 ^~~~~~~~~~~~~~~~~~~~~
./include/linux/bitops.h:53:32: note: in definition of macro 'bitop'
   53 |          const##op(nr, addr) : op(nr, addr))
      |                                ^~
./include/linux/bitops.h:62:47: note: in expansion of macro '_test_bit_acquire'
   62 | #define test_bit_acquire(nr, addr)      bitop(_test_bit_acquire, nr, addr)
      |                                               ^~~~~~~~~~~~~~~~~
./include/linux/wait_bit.h:74:14: note: in expansion of macro 'test_bit_acquire'
   74 |         if (!test_bit_acquire(bit, word))
      |              ^~~~~~~~~~~~~~~~

s390 error is:

In file included from ./arch/s390/include/asm/bitops.h:211,
                 from ./include/linux/bitops.h:68,
                 from ./include/linux/log2.h:12,
                 from kernel/bounds.c:13:
./include/asm-generic/bitops/instrumented-non-atomic.h: In function '_test_bit_acquire':
./include/asm-generic/bitops/instrumented-non-atomic.h:154:16: error: implicit declaration of function 'arch_test_bit_acquire'; did you mean '_test_bit_acquire'? [-Werror=implicit-function-declaration]
  154 |         return arch_test_bit_acquire(nr, addr);
      |                ^~~~~~~~~~~~~~~~~~~~~
      |                _test_bit_acquire


git bisect pointed to 8238b4579866 ("wait_on_bit: add an acquire memory barrier").
And, reverting that commit has fixed the build failure.

I will be happy to test any patch or provide any extra log if needed.

--
Regards
Sudip