Re: [PATCH v2 10/10] s390/maccess: Remove spinlock from __s390_kernel_write()

[sashiko-bot@kernel.org]

> The spinlock in __s390_kernel_write() was introduced to serialize the
> read-modify-write sequence against concurrent callers. Now that all
> runtime callers of s390_kernel_write() hold the text_mutex, the
> spinlock is not required anymore.
> 
> Replace it with preempt_disable() / preempt_enable() and sync_core().
> Previously, CPU serialization was implicitly done by other
> instructions. Make this explicit with sync_core() instead of
> relying on that.
> 
> Preemption is disabled so that sync_core() issues the CPU serialization
> instruction on the same CPU that executed the stores. This completes all
> previous stores and makes them visible to other CPUs.
> 
> Other CPUs need to perform CPU serialization, e.g. with text_poke_sync(),
> [ ... ]
> Work around that by calling the non-checking __s390_kernel_write(),
> and add lockdep_assert_held() checks to arch_arm_kprobe() and
> arch_disarm_kprobe().
> 
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261027143030.3154657-1-hca@linux.ibm.com?part=10