linux-kernel - [PATCH] kernel/panic/kexec: fix "crash_kexec_post

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Date:	Thu, 05 Feb 2015 17:59:43 +0900 (JST)
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	ebiederm@...ssion.com, vgoyal@...hat.com
Cc:	masami.hiramatsu.pt@...achi.com, linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org
Subject: [PATCH] kernel/panic/kexec: fix "crash_kexec_post_notifiers"
 option issue in oops path

The commit f06e5153f4ae2e2f3b0300f0e260e40cb7fefd45 introduced
"crash_kexec_post_notifiers" kernel boot option, which toggles
wheather panic() calls crash_kexec() before or after panic_notifiers
and dump kmsg.

The problem is that the commit overlooks panic_on_oops kernel boot
option. If it is enabled, crash_kexec() is called directly without
going through panic() in oops path.

To fix this issue, this patch adds a check to
"crash_kexec_post_notifiers" in the condition of kexec_should_crash().

Signed-off-by: HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
---
 include/linux/kernel.h | 3 +++
 kernel/kexec.c         | 2 ++
 kernel/panic.c         | 2 +-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 64ce58b..f47379f 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -426,6 +426,9 @@ extern int panic_on_unrecovered_nmi;
 extern int panic_on_io_nmi;
 extern int panic_on_warn;
 extern int sysctl_panic_on_stackoverflow;
+
+extern bool crash_kexec_post_notifiers;
+
 /*
  * Only to be used by arch init code. If the user over-wrote the default
  * CONFIG_PANIC_TIMEOUT, honor it.
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 9a8a01a..0ecf252 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -84,6 +84,8 @@ struct resource crashk_low_res = {
 
 int kexec_should_crash(struct task_struct *p)
 {
+	if (crash_kexec_post_notifiers)
+		return 0;
 	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
 		return 1;
 	return 0;
diff --git a/kernel/panic.c b/kernel/panic.c
index 4d8d6f9..6582546 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -32,7 +32,7 @@ static unsigned long tainted_mask;
 static int pause_on_oops;
 static int pause_on_oops_flag;
 static DEFINE_SPINLOCK(pause_on_oops_lock);
-static bool crash_kexec_post_notifiers;
+bool crash_kexec_post_notifiers;
 int panic_on_warn __read_mostly;
 
 int panic_timeout = CONFIG_PANIC_TIMEOUT;
-- 
1.9.3


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