[PATCH v3 0/3] Introduce arch_do_panic

[Mete Durlu <meted@linux.ibm.com>]

Changes in v3:
- Use __weak functions instead of symbol override via ifdef
- Patch 2: Better explain what is fixed (Bradley Morgan)
- Add statements about print order changes (Bradley Morgan)
- Patch 2: Add a pr_warn() to notify user about on_panic and
  panic_timeout relationship if they try to assign a trigger to
  on_panic action while panic_timeout is set to a value other than 0
  (Bradley Morgan)

Changes in v2 - Address Sashiko findings;
- Patch 2: Remove unused leftover code
- Patch 2: Mention panic_timeout and shutdown_actions relationship for
  s390 in commit message
- Patch 3: Use bug.h instead of setup.h to pass around arch_do_panic
  implementation of sparc

Replace architecture-specific ifdef sections in vpanic() with a clean
arch_do_panic() hook. Currently s390 and sparc embed their panic
handlers directly in vpanic() using preprocessor conditionals, making
the common code path harder to maintain.

Introduce arch_do_panic() as an architecture extension point called at
the end of vpanic(). Architectures can use this hook to implement their
specific panic handling without polluting the generic panic code.

Move s390 panic handling from the panic_notifier chain to
arch_do_panic(). This corrects the execution order so that the
panic_timeout is properly evaluated before architecture-specific
actions. Reordering also allows more information to be printed during
panic a for s390. sys_info(), kmsg_dump_desc(), etc... are now
reachable.

Move sparc panic handling from ifdef blocks to arch_do_panic(). Remove
the preprocessor conditionals from vpanic() and place the Stop-A
enablement code in architecture-specific files where it belongs.
Stop-A enablement markers are now printed after "end Kernel panic"
line.

The cleanup reduces vpanic() complexity and establishes a pattern for other
architectures needing custom panic behavior.

Signed-off-by: Mete Durlu <meted@linux.ibm.com>
---
Mete Durlu (3):
      panic: Introduce arch_do_panic
      s390: Implement arch_do_panic
      sparc: Implement arch_do_panic

 arch/s390/kernel/ipl.c    | 19 +++++--------------
 arch/sparc/kernel/setup.c |  8 ++++++++
 include/linux/panic.h     |  2 ++
 kernel/panic.c            | 15 +++------------
 4 files changed, 18 insertions(+), 26 deletions(-)
---
base-commit: 48a5a7ab8d6ab7090564339e039c421f315de912
change-id: 20260724-arch_do_panic-a97f699aa332

Best regards,
-- 
Mete Durlu <meted@linux.ibm.com>