next-20250825: arc: seqlock.h:876:2: error: implicit declaration of function 'spin_lock' [-Werror=implicit-function-declaration]

[Naresh Kamboju]

The following build warnings / errors noticed with arc defconfig with
gcc-9 toolchain.

Regression Analysis:
- New regression? yes
- Reproducibility? yes

Build regression: next-20250825 arc seqlock.h:876:2: error: implicit
declaration of function 'spin_lock'
[-Werror=implicit-function-declaration]

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>

arc:
  build:
    * gcc-9-allnoconfig
    * gcc-9-tinyconfig
    * gcc-9-vdk_hs38_smp_defconfig
    * gcc-9-defconfig
    * gcc-9-axs103_defconfig

## Build log
In file included from include/linux/mmzone.h:17,
                 from include/linux/gfp.h:7,
                 from include/linux/mm.h:7,
                 from arch/arc/include/asm/arcregs.h:149,
                 from arch/arc/include/asm/irqflags-arcv2.h:9,
                 from arch/arc/include/asm/irqflags.h:13,
                 from include/linux/irqflags.h:18,
                 from include/linux/spinlock.h:59,
                 from include/linux/sched.h:37,
                 from arch/arc/kernel/asm-offsets.c:6:
include/linux/seqlock.h: In function 'write_seqlock':
include/linux/seqlock.h:876:2: error: implicit declaration of function
'spin_lock' [-Werror=implicit-function-declaration]
  876 |  spin_lock(&sl->lock);
      |  ^~~~~~~~~
include/linux/seqlock.h: In function 'write_sequnlock':
include/linux/seqlock.h:890:2: error: implicit declaration of function
'spin_unlock' [-Werror=implicit-function-declaration]
  890 |  spin_unlock(&sl->lock);
      |  ^~~~~~~~~~~
include/linux/seqlock.h: In function 'write_seqlock_bh':
include/linux/seqlock.h:902:2: error: implicit declaration of function
'spin_lock_bh' [-Werror=implicit-function-declaration]
  902 |  spin_lock_bh(&sl->lock);
      |  ^~~~~~~~~~~~
include/linux/seqlock.h: In function 'write_sequnlock_bh':
include/linux/seqlock.h:917:2: error: implicit declaration of function
'spin_unlock_bh' [-Werror=implicit-function-declaration]
  917 |  spin_unlock_bh(&sl->lock);
      |  ^~~~~~~~~~~~~~
include/linux/seqlock.h: In function 'write_seqlock_irq':
include/linux/seqlock.h:929:2: error: implicit declaration of function
'spin_lock_irq' [-Werror=implicit-function-declaration]
  929 |  spin_lock_irq(&sl->lock);
      |  ^~~~~~~~~~~~~
include/linux/seqlock.h: In function 'write_sequnlock_irq':
include/linux/seqlock.h:943:2: error: implicit declaration of function
'spin_unlock_irq'; did you mean 'write_sequnlock_irq'?
[-Werror=implicit-function-declaration]
  943 |  spin_unlock_irq(&sl->lock);
      |  ^~~~~~~~~~~~~~~
      |  write_sequnlock_irq
include/linux/seqlock.h: In function '__write_seqlock_irqsave':
include/linux/seqlock.h:950:2: error: implicit declaration of function
'spin_lock_irqsave' [-Werror=implicit-function-declaration]
  950 |  spin_lock_irqsave(&sl->lock, flags);
      |  ^~~~~~~~~~~~~~~~~
include/linux/seqlock.h: In function 'write_sequnlock_irqrestore':
include/linux/seqlock.h:981:2: error: implicit declaration of function
'spin_unlock_irqrestore'; did you mean 'write_sequnlock_irqrestore'?
[-Werror=implicit-function-declaration]
  981 |  spin_unlock_irqrestore(&sl->lock, flags);
      |  ^~~~~~~~~~~~~~~~~~~~~~
      |  write_sequnlock_irqrestore
In file included from include/linux/sched.h:15,
                 from arch/arc/kernel/asm-offsets.c:6:
include/linux/rcupdate.h: In function 'rcu_read_lock_sched_held':
include/linux/preempt.h:227:49: error: implicit declaration of
function 'irqs_disabled' [-Werror=implicit-function-declaration]
  227 | #define preemptible() (preempt_count() == 0 && !irqs_disabled())
      |                                                 ^~~~~~~~~~~~~
                          ^
cc1: some warnings being treated as errors

## Source
* Kernel version: 6.17.0-rc3-next-20250825
* Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
* Git describe: next-20250825
* Git commit: 6c68f4c0a147c025ae0b25fab688c7c47964a02f
* Architectures: arc
* Toolchains: gcc-9
* Kconfigs: defconfig

## Build
* Build log: https://qa-reports.linaro.org/api/testruns/29652436/log_file/
* Build details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250825/build/gcc-9-defconfig/
* Build error details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250825/log-parser-build-gcc/gcc-compiler-include_asm-generic_getorder_h-error-implicit-declaration-of-function-ilog/
* Build plan: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/31lrYki7MzYyqtJKnutAe2oawoq
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/31lrYki7MzYyqtJKnutAe2oawoq/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/31lrYki7MzYyqtJKnutAe2oawoq/config

--
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https://lkft.linaro.org