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

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Message-ID: <20160705113323.5864.66834.stgit@softrs>
Date:	Tue, 05 Jul 2016 20:33:23 +0900
From:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Young <dyoung@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Baoquan He <bhe@...hat.com>
Cc:	x86@...nel.org, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Daniel Walker <dwalker@...o99.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
	Vivek Goyal <vgoyal@...hat.com>
Subject: [V3 PATCH 0/2] kexec: crash_kexec_post_notifiers boot option
 related fixes

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