[PATCH 00/11] Refcounted interrupt disable and SpinLockIrq for rust (Part 1)

[Boqun Feng <boqun@kernel.org>]

Hi Peter,

This is a follow-up for Lyude's work [1]. Per your feedback at [2], I
did some digging and turned out that ARM64 already kinda did this. The
basic idea is based on:

1) preempt_count() previously mask our NEED_RESCHED bit, so the
   effective bits is 31bits
2) with a 64bit preempt count implementation (as in your PREEMPT_LONG
   proposal), the effective bits that record "whether we CAN preempt or
   not" still fit in 32bit (i.e. an int)

as a result, I don't think we need to change the existing
preempt_count() API, but rather keep "32bit vs 64bit" as an
implementation detail. This saves us the need to change the printk code
for preempt_count().

For people who have reviewed the previous version, patch 8-11 are new,
please take a look.

The patchset passed the build and booting tests and also a "perf record"
test on x86 for NMI code path.

I would like to target this changes for 7.2 if possible.

[1]: https://lore.kernel.org/all/20260121223933.1568682-1-lyude@redhat.com/
[2]: https://lore.kernel.org/all/20260204111234.GA3031506@noisy.programming.kicks-ass.net/

Regards,
Boqun

Boqun Feng (8):
  preempt: Introduce HARDIRQ_DISABLE_BITS
  preempt: Introduce __preempt_count_{sub, add}_return()
  irq & spin_lock: Add counted interrupt disabling/enabling
  locking: Switch to _irq_{disable,enable}() variants in cleanup guards
  sched: Remove the unused preempt_offset parameter of __cant_sleep()
  sched: Avoid signed comparison of preempt_count() in __cant_migrate()
  preempt: Introduce PREEMPT_COUNT_64BIT
  arm64: sched/preempt: Enable PREEMPT_COUNT_64BIT

Joel Fernandes (1):
  preempt: Track NMI nesting to separate per-CPU counter

Lyude Paul (2):
  openrisc: Include <linux/cpumask.h> in smp.h
  irq: Add KUnit test for refcounted interrupt enable/disable

 arch/arm64/Kconfig                   |   1 +
 arch/arm64/include/asm/preempt.h     |  18 +++++
 arch/openrisc/include/asm/smp.h      |   2 +
 arch/s390/include/asm/preempt.h      |  10 +++
 arch/x86/Kconfig                     |   1 +
 arch/x86/include/asm/preempt.h       |  61 +++++++++++----
 arch/x86/kernel/cpu/common.c         |   2 +-
 include/asm-generic/preempt.h        |  14 ++++
 include/linux/hardirq.h              |  41 ++++++++--
 include/linux/interrupt_rc.h         |  63 ++++++++++++++++
 include/linux/kernel.h               |   4 +-
 include/linux/preempt.h              |  35 ++++++---
 include/linux/spinlock.h             |  51 +++++++++----
 include/linux/spinlock_api_smp.h     |  27 +++++++
 include/linux/spinlock_api_up.h      |   9 +++
 include/linux/spinlock_rt.h          |  15 ++++
 kernel/Kconfig.preempt               |   4 +
 kernel/irq/Makefile                  |   1 +
 kernel/irq/refcount_interrupt_test.c | 109 +++++++++++++++++++++++++++
 kernel/locking/spinlock.c            |  29 +++++++
 kernel/sched/core.c                  |  18 +++--
 kernel/softirq.c                     |  11 +++
 lib/locking-selftest.c               |   2 +-
 23 files changed, 476 insertions(+), 52 deletions(-)
 create mode 100644 include/linux/interrupt_rc.h
 create mode 100644 kernel/irq/refcount_interrupt_test.c

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