linux-kernel - [v2 PATCH 3/3] hpwdt: Use nmi_panic() when kernel panics in NMI handler

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Date:	Wed, 02 Mar 2016 19:36:31 +0900
From:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Mingarelli <thomas.mingarelli@....com>,
	Wim Van Sebroeck <wim@...ana.be>,
	Corey Minyard <minyard@....org>
Cc:	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
	Michal Hocko <mhocko@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	openipmi-developer@...ts.sourceforge.net,
	Guenter Roeck <linux@...ck-us.net>
Subject: [v2 PATCH 3/3] hpwdt: Use nmi_panic() when kernel panics in NMI
 handler

commit 1717f2096b54 ("panic, x86: Fix re-entrance problem due to
panic on NMI") introduced nmi_panic() which prevents concurrent and
recursive execution of panic().  It also saves registers for the
crash dump on x86 by later commit 58c5661f2144 ("panic, x86: Allow
CPUs to save registers even if looping in NMI context").

hpwdt driver can call panic() from NMI handler, so replace it with
nmi_panic().  Also, do some cleanups.

Changes since V1:
- Use direct return instead of goto
- Combine the panic message string into a single line

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
Cc: Thomas Mingarelli <thomas.mingarelli@....com>
Cc: Wim Van Sebroeck <wim@...ana.be>
Cc: Guenter Roeck <linux@...ck-us.net>
Cc: linux-watchdog@...r.kernel.org
---
 drivers/watchdog/hpwdt.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index 92443c3..a6c8797 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -483,7 +483,7 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
 	static int die_nmi_called;
 
 	if (!hpwdt_nmi_decoding)
-		goto out;
+		return NMI_DONE;
 
 	spin_lock_irqsave(&rom_lock, rom_pl);
 	if (!die_nmi_called && !is_icru && !is_uefi)
@@ -496,11 +496,11 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
 
 	if (!is_icru && !is_uefi) {
 		if (cmn_regs.u1.ral == 0) {
-			panic("An NMI occurred, "
-				"but unable to determine source.\n");
+			nmi_panic(regs, "An NMI occurred, but unable to determine source.\n");
+			return NMI_HANDLED;
 		}
 	}
-	panic("An NMI occurred. Depending on your system the reason "
+	nmi_panic(regs, "An NMI occurred. Depending on your system the reason "
 		"for the NMI is logged in any one of the following "
 		"resources:\n"
 		"1. Integrated Management Log (IML)\n"
@@ -508,8 +508,7 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
 		"3. OA Forward Progress Log\n"
 		"4. iLO Event Log");
 
-out:
-	return NMI_DONE;
+	return NMI_HANDLED;
 }
 #endif /* CONFIG_HPWDT_NMI_DECODING */