[PATCH -tip] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop()

[PATCH -tip] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop()

[Seiji Aguchi]

Hi,

 As Don mentioned in following thread, it would be nice for pstore/kmsg_dump to serialize  
panic path because they can log messages reliably.

 https://lkml.org/lkml/2011/10/13/427

 This patch is based on Don's proposal switching smp_send_stop() from REBOOT_VECTOR to NMI 
 which has already merged to -tip tree.
 
 https://lkml.org/lkml/2012/5/14/145

[Patch Description]
This patch just moves kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop  for serializing 
logging process via smp_send_stop.

 Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
 Acked-by: Don Zickus <dzickus@redhat.com>

---
 kernel/panic.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c index 80aed44..da585b8 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
 	 */
 	crash_kexec(NULL);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic @@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
 	 */
 	smp_send_stop();
 
+	kmsg_dump(KMSG_DUMP_PANIC);
+
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
 	bust_spinlocks(0);
-- 1.7.1

[tip:core/debug] kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

[tip-bot for Seiji Aguchi]

Commit-ID:  f80f749132165fb083865e51afd65cf0f05dcd62
Gitweb:     http://git.kernel.org/tip/f80f749132165fb083865e51afd65cf0f05dcd62
Author:     Seiji Aguchi <seiji.aguchi@hds.com>
AuthorDate: Tue, 15 May 2012 17:35:09 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 18 May 2012 10:07:37 +0200

kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

This patch moves kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop(),
to serialize the crash-logging process via smp_send_stop() and to
thus retrieve a more stable crash image of all CPUs stopped.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: dle-develop@lists.sourceforge.net <dle-develop@lists.sourceforge.net>
Cc: Satoru Moriya <satoru.moriya@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: a.p.zijlstra@chello.nl <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/5C4C569E8A4B9B42A84A977CF070A35B2E4D7A5CE2@USINDEVS01.corp.hds.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/panic.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index b6215b7..d4f0b61 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
 	 */
 	crash_kexec(NULL);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic

Re: [tip:core/debug] kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

[Peter Zijlstra]

On Fri, 2012-05-18 at 03:49 -0700, tip-bot for Seiji Aguchi wrote:

> kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()
> 
> This patch moves kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop(),
> to serialize the crash-logging process via smp_send_stop() and to
> thus retrieve a more stable crash image of all CPUs stopped.

I don't want to be a spoil sport or anything, but this patch doesn't
move anything, it just removes..

> ---
>  kernel/panic.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/panic.c b/kernel/panic.c
> index b6215b7..d4f0b61 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
>  	 */
>  	crash_kexec(NULL);
>  
> -	kmsg_dump(KMSG_DUMP_PANIC);
> -
>  	/*
>  	 * Note smp_send_stop is the usual smp shutdown function, which
>  	 * unfortunately means it may not be hardened to work in a panic

Re: [tip:core/debug] kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

[Ingo Molnar]

* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Fri, 2012-05-18 at 03:49 -0700, tip-bot for Seiji Aguchi wrote:
> 
> > kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()
> > 
> > This patch moves kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop(),
> > to serialize the crash-logging process via smp_send_stop() and to
> > thus retrieve a more stable crash image of all CPUs stopped.
> 
> I don't want to be a spoil sport or anything, but this patch doesn't
> move anything, it just removes..

Hm, indeed. And the patch in the email is fine. I think I messed 
up a conflict resolution ...

Should be fixed now.

Thanks,

	Ingo

[tip:core/debug] kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

[tip-bot for Seiji Aguchi]

Commit-ID:  62be73eafaa045d3233337303fb140f7f8a61135
Gitweb:     http://git.kernel.org/tip/62be73eafaa045d3233337303fb140f7f8a61135
Author:     Seiji Aguchi <seiji.aguchi@hds.com>
AuthorDate: Tue, 15 May 2012 17:35:09 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 18 May 2012 14:02:10 +0200

kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()

This patch moves kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop(),
to serialize the crash-logging process via smp_send_stop() and to
thus retrieve a more stable crash image of all CPUs stopped.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: dle-develop@lists.sourceforge.net <dle-develop@lists.sourceforge.net>
Cc: Satoru Moriya <satoru.moriya@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: a.p.zijlstra@chello.nl <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/5C4C569E8A4B9B42A84A977CF070A35B2E4D7A5CE2@USINDEVS01.corp.hds.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/panic.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index b6215b7..d2a5f4e 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
 	 */
 	crash_kexec(NULL);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic
@@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
 	 */
 	smp_send_stop();
 
+	kmsg_dump(KMSG_DUMP_PANIC);
+
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
 	bust_spinlocks(0);