This series introduces a family of helper functions to manage panic state and
updates existing code to use them.

Before this series, panic state helpers were scattered and inconsistent. For
example, panic_in_progress() was defined in printk/printk.c, not in panic.c or
panic.h. As a result, developers had to look in unexpected places to understand
or re-use panic state logic. Other checks were open- coded, duplicating logic
across panic, crash, and watchdog paths.

The new helpers centralize the functionality in panic.c/panic.h:
  - panic_try_start()
  - panic_reset()
  - panic_in_progress()
  - panic_on_this_cpu()
  - panic_on_other_cpu()

Patches 1–8 add the helpers and convert panic/crash and printk/nbcon code to
use them.

Patch 9 fixes a bug in the watchdog subsystem by skipping checks when a panic
is in progress, avoiding interference with the panic CPU.

Together, this makes panic state handling simpler, more discoverable, and more
robust.

-- 

Changes from v1:

  - The commit messages have been re-formatted based on Baoquan He's suggestions.
  - The panic_in_progress() check has been moved to be the first check in
    watchdog_overflow_callback(), as suggested by Yury Norov.

Link to v1:
https://lore.kernel.org/all/20250820091702.512524-1-wangjinchao600@gmail.com/

Jinchao Wang (9):
  panic: Introduce helper functions for panic state
  fbdev: Use panic_in_progress() helper
  crash_core: use panic_try_start() in crash_kexec()
  panic: use panic_try_start() in nmi_panic()
  panic: use panic_try_start() in vpanic()
  printk/nbcon: use panic_on_this_cpu() helper
  panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu()
  panic/printk: replace other_cpu_in_panic() with panic_on_other_cpu()
  watchdog: skip checks when panic is in progress

 drivers/video/fbdev/core/fbcon.c  |  9 +---
 include/linux/panic.h             |  6 +++
 include/linux/printk.h            |  2 -
 kernel/crash_core.c               | 15 ++-----
 kernel/panic.c                    | 71 +++++++++++++++++++++++++------
 kernel/printk/internal.h          |  1 -
 kernel/printk/nbcon.c             | 14 +++---
 kernel/printk/printk.c            | 37 +++-------------
 kernel/printk/printk_ringbuffer.c |  2 +-
 kernel/watchdog.c                 |  6 +++
 kernel/watchdog_perf.c            |  4 ++
 lib/dump_stack.c                  |  2 +-
 12 files changed, 91 insertions(+), 78 deletions(-)

-- 
2.43.0