linux-kernel - [PATCH] kernel/watchdog: use nmi registers snapshot in hardlockup handler

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Message-ID: <146771764784.86724.6006627197118544150.stgit@buzz>
Date:	Tue, 05 Jul 2016 14:20:47 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Aaron Tomlin <atomlin@...hat.com>
Subject: [PATCH] kernel/watchdog: use nmi registers snapshot in hardlockup
 handler

NMI handler doesn't call set_irq_regs(), so get_irq_regs() returns NULL or
stale snapshot from beginning of IRQ interrupted by NMI. Registers from
argument are always here and points to interrupted instruction and state.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc: Jiri Kosina <jkosina@...e.cz>
---
 kernel/watchdog.c |    1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9acb29f280ec..6d1020c03d41 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -344,7 +344,6 @@ static void watchdog_overflow_callback(struct perf_event *event,
 	 */
 	if (is_hardlockup()) {
 		int this_cpu = smp_processor_id();
-		struct pt_regs *regs = get_irq_regs();
 
 		/* only print hardlockups once */
 		if (__this_cpu_read(hard_watchdog_warn) == true)