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Date: Tue, 12 Jun 2018 17:57:42 -0700
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>
Cc: Andi Kleen <andi.kleen@...el.com>, Ashok Raj <ashok.raj@...el.com>,
Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>, x86@...nel.org,
sparclinux@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org,
Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
Jacob Pan <jacob.jun.pan@...el.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Don Zickus <dzickus@...hat.com>,
Nicholas Piggin <npiggin@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Frederic Weisbecker <frederic@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Babu Moger <babu.moger@...cle.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Philippe Ombredanne <pombredanne@...b.com>,
Colin Ian King <colin.king@...onical.com>,
Byungchul Park <byungchul.park@....com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
"Luis R. Rodriguez" <mcgrof@...nel.org>,
Waiman Long <longman@...hat.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Randy Dunlap <rdunlap@...radead.org>,
Davidlohr Bueso <dave@...olabs.net>,
Christoffer Dall <cdall@...aro.org>,
Marc Zyngier <marc.zyngier@....com>,
Kai-Heng Feng <kai.heng.feng@...onical.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
David Rientjes <rientjes@...gle.com>,
iommu@...ts.linux-foundation.org
Subject: [RFC PATCH 22/23] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter
Keep the HPET-based hardlockup detector disabled unless explicitly enabled
via a command line argument. If such parameter is not given, the hardlockup
detector will fallback to use the perf-based implementation.
The function hardlockup_panic_setup() is updated to return 0 in order to
to allow __setup functions of specific hardlockup detectors (in this case
hardlockup_detector_hpet_setup()) to inspect the nmi_watchdog boot
parameter.
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Andi Kleen <andi.kleen@...el.com>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Jacob Pan <jacob.jun.pan@...el.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc: Don Zickus <dzickus@...hat.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Frederic Weisbecker <frederic@...nel.org>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Babu Moger <babu.moger@...cle.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Philippe Ombredanne <pombredanne@...b.com>
Cc: Colin Ian King <colin.king@...onical.com>
Cc: Byungchul Park <byungchul.park@....com>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Randy Dunlap <rdunlap@...radead.org>
Cc: Davidlohr Bueso <dave@...olabs.net>
Cc: Christoffer Dall <cdall@...aro.org>
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Cc: x86@...nel.org
Cc: iommu@...ts.linux-foundation.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
--
checkpatch gives the following warning:
CHECK: __setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst
+__setup("nmi_watchdog=", hardlockup_detector_hpet_setup);
This is a false-positive as the option nmi_watchdog is already
documented. The option is re-evaluated in this file as well.
---
Documentation/admin-guide/kernel-parameters.txt | 5 ++++-
kernel/watchdog.c | 2 +-
kernel/watchdog_hld_hpet.c | 13 +++++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f2040d4..a8833c7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2577,7 +2577,7 @@
Format: [state][,regs][,debounce][,die]
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
- Format: [panic,][nopanic,][num]
+ Format: [panic,][nopanic,][num,][hpet]
Valid num: 0 or 1
0 - turn hardlockup detector in nmi_watchdog off
1 - turn hardlockup detector in nmi_watchdog on
@@ -2587,6 +2587,9 @@
please see 'nowatchdog'.
This is useful when you use a panic=... timeout and
need the box quickly up again.
+ When hpet is specified, the NMI watchdog will be driven
+ by an HPET timer, if available in the system. Otherwise,
+ the perf-based implementation will be used.
These settings can be accessed at runtime via
the nmi_watchdog and hardlockup_panic sysctls.
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index b94bbe3..b5ce6e4 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -84,7 +84,7 @@ static int __init hardlockup_panic_setup(char *str)
nmi_watchdog_user_enabled = 0;
else if (!strncmp(str, "1", 1))
nmi_watchdog_user_enabled = 1;
- return 1;
+ return 0;
}
__setup("nmi_watchdog=", hardlockup_panic_setup);
diff --git a/kernel/watchdog_hld_hpet.c b/kernel/watchdog_hld_hpet.c
index ebb820d..12e5937 100644
--- a/kernel/watchdog_hld_hpet.c
+++ b/kernel/watchdog_hld_hpet.c
@@ -17,6 +17,7 @@
#define pr_fmt(fmt) "NMI hpet watchdog: " fmt
static struct hpet_hld_data *hld_data;
+static bool hardlockup_use_hpet;
/**
* get_count() - Get the current count of the HPET timer
@@ -488,6 +489,15 @@ static void hardlockup_detector_hpet_stop(void)
spin_unlock(&hld_data->lock);
}
+static int __init hardlockup_detector_hpet_setup(char *str)
+{
+ if (strstr(str, "hpet"))
+ hardlockup_use_hpet = true;
+
+ return 0;
+}
+__setup("nmi_watchdog=", hardlockup_detector_hpet_setup);
+
/**
* hardlockup_detector_hpet_init() - Initialize the hardlockup detector
*
@@ -502,6 +512,9 @@ static int __init hardlockup_detector_hpet_init(void)
{
int ret;
+ if (!hardlockup_use_hpet)
+ return -EINVAL;
+
if (!is_hpet_enabled())
return -ENODEV;
--
2.7.4
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