linux-kernel - [RFC][PATCH v4 -next 3/4]Skip subsequent kmsg

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Message-ID: <5C4C569E8A4B9B42A84A977CF070A35B2C5827AF86@USINDEVS01.corp.hds.com>
Date:	Thu, 5 Jan 2012 12:39:59 -0500
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"Luck, Tony" <tony.luck@...el.com>, Don Zickus <dzickus@...hat.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Matthew Garrett <mjg@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"Chen, Gong" <gong.chen@...el.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"Brown, Len" <len.brown@...el.com>,
	"'ying.huang@...el.com'" <'ying.huang@...el.com'>,
	"'ak@...ux.intel.com'" <'ak@...ux.intel.com'>,
	"'hughd@...omium.org'" <'hughd@...omium.org'>,
	"'mingo@...e.hu'" <'mingo@...e.hu'>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"namhyung@...il.com" <namhyung@...il.com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: [RFC][PATCH v4 -next 3/4]Skip subsequent kmsg_dump() function calls
 in panic path

This patch skips subsequent kmsg_dump() function calls in panic path

With this patch, we can avoid deadlock due to the subsequent calls.
Actually, kmsg_dump(KMSG_DUMP_EMREG) is called after kmsg_dump(KMSG_DUMP_PANIC) 
when panic_timeout variable is set.

 Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>

---
 kernel/printk.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/kernel/printk.c b/kernel/printk.c
index 5294426..186d792 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1731,6 +1731,16 @@ void kmsg_dump(enum kmsg_dump_reason reason)
 	const char *s1, *s2;
 	unsigned long l1, l2;
 	unsigned long flags;
+	static bool panicked;
+
+	/*
+	 * kmsg_dump() is skipped because we already got panic log.
+	 */
+	if (panicked)
+		return;
+
+	if (reason == KMSG_DUMP_PANIC)
+		panicked = true;
 
 	/*
 	 * Currently, "in_nmi() && reason != KMSG_DUMP_PANIC" case never happens
-- 
1.7.1


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