[V3 PATCH 0/2] kexec: crash_kexec_post_notifiers boot option related fixes

[Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>]

This is the update version of the patch which I posted one year ago
(https://lkml.org/lkml/2015/7/23/864).  Because I couldn't received
positive opinions against the previous version, I had changed the
approach to another one which utilizes kexec purgatory.  Then I'm
back here.

PATCH 1/2 is a bugfix for crash_kexec_post_notifiers boot option
which allows users to call panic notifiers and kmsg dumpers before
kdump.  When this option is enabled, smp_send_stop() is used to stop
other CPUs instead of a function provided by kdump.  smp_send_stop()
just stops other CPUs and doesn't other things needed for kdump.
So, fix it by replacing smp_send_stop() with new appropriate one,
panic_smp_send_stop().  Since panic_smp_send_stop() is architecture
specific and I can't simply copy from kdump routines, only
x86-specific version is provided.

PATCH 2/2 makes crash_kexec_post_notifiers boot option modifiable
after boot.  We don't need to limit it to being modifiable at boot
time.

Changes in V3:
- Revise comments, description, and symbol names (the logic doesn't
  change)
- Make crash_kexec_post_notifiers boot option modifiable after boot

Changes in V2: https://lkml.org/lkml/2015/7/23/864
- Replace smp_send_stop() call with crash_kexec version which
  saves cpu states and does cleanups instead of changing execution
  flow
- Drop a fix for Problem 1
- Drop other patches because they aren't needed anymore

V1: https://lkml.org/lkml/2015/7/10/316

---

Hidehiro Kawai (2):
      x86/panic: Replace smp_send_stop() with kdump friendly version
      kexec: Use core_param for crash_kexec_post_notifiers boot option


 arch/x86/kernel/crash.c |   14 ++++++++----
 kernel/panic.c          |   56 ++++++++++++++++++++++++++++++-----------------
 2 files changed, 46 insertions(+), 24 deletions(-)


-- 
Hidehiro Kawai
Hitachi, Ltd. Research & Development Group