linux-kernel - [PATCH] V6 init/main.c Enable watchdog_thresh control from kernel line To: loberman@...hat.com

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Message-Id: <1540410119-21120-1-git-send-email-loberman@redhat.com>
Date:   Wed, 24 Oct 2018 15:41:59 -0400
From:   Laurence Oberman <loberman@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     rdunlap@...radead.org, tglx@...utronix.de,
        Laurence Oberman <loberman@...hat.com>
Subject: [PATCH] V6 init/main.c Enable watchdog_thresh control from kernel  line To: loberman@...hat.com

Both graphics and serial consoles are exposed to hard lockups
when handling a large amount of messaging. The kernel watchdog_thresh
parameter up to now has not been available to be set on the kernel line for
early boot.
This patch allows the setting of watchdog_thresh to be increased
when needed to avoid the hard lockups in the console code.

Signed-off-by: Laurence Oberman <loberman@...hat.com>
Acked-by: Randy Dunlap <rdunlap@...radead.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  7 +++++++
 init/main.c                                     | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4cdcd1a..102382f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4932,6 +4932,13 @@
 			or other driver-specific files in the
 			Documentation/watchdog/ directory.
 
+	watchdog_thresh=
+			This parameter allows early boot to change the
+			value of the watchdog timeout threshold from the default
+			of 10 seconds to avoid hard lockups.  Example:
+			watchdog_thresh=30
+			Default: 10
+
 	workqueue.watchdog_thresh=
 			If CONFIG_WQ_WATCHDOG is configured, workqueue can
 			warn stall conditions and dump internal state to
diff --git a/init/main.c b/init/main.c
index 1c3f902..d5511a9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1038,6 +1038,17 @@ static int __init set_debug_rodata(char *str)
 __setup("rodata=", set_debug_rodata);
 #endif
 
+#ifdef CONFIG_LOCKUP_DETECTOR
+extern int watchdog_thresh;
+
+static int __init watchdog_thresh_setup(char *str)
+{
+	get_option(&str, &watchdog_thresh);
+	return 1;
+}
+__setup("watchdog_thresh=", watchdog_thresh_setup);
+#endif
+
 #ifdef CONFIG_STRICT_KERNEL_RWX
 static void mark_readonly(void)
 {
-- 
1.8.3.1