linux-kernel - [RFC PATCH v2 10/14] kernel/watchdog: Add a function to obtain the watchdog_allowed

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Message-Id: <1551283518-18922-11-git-send-email-ricardo.neri-calderon@linux.intel.com>
Date:   Wed, 27 Feb 2019 08:05:14 -0800
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>
Cc:     Ashok Raj <ashok.raj@...el.com>, Andi Kleen <andi.kleen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri@...el.com>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Tony Luck <tony.luck@...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>,
        Paul Mackerras <paulus@...ba.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Masami Hiramatsu <mhiramat@...nel.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>,
        "David S. Miller" <davem@...emloft.net>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        sparclinux@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v2 10/14] kernel/watchdog: Add a function to obtain the watchdog_allowed_mask

Implementations of NMI watchdogs that use a single piece of hardware to
monitor all the CPUs in the system (as opposed to per-CPU implementations
such as perf) need to know which CPUs the watchdog is allowed to monitor.
In this manner, non-maskable interrupts are directed only to the monitored
CPUs.

Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Andi Kleen <andi.kleen@...el.com>
Cc: Tony Luck <tony.luck@...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: Paul Mackerras <paulus@...ba.org>
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: "David S. Miller" <davem@...emloft.net>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: sparclinux@...r.kernel.org
Cc: linuxppc-dev@...ts.ozlabs.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
 include/linux/nmi.h | 1 +
 kernel/watchdog.c   | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index bf5ebcfdd590..b563fb6ef21d 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -83,6 +83,7 @@ static inline void reset_hung_task_detector(void) { }
 
 #if defined(CONFIG_HARDLOCKUP_DETECTOR)
 extern void hardlockup_detector_disable(void);
+extern struct cpumask *watchdog_get_allowed_cpumask(void);
 extern unsigned int hardlockup_panic;
 #else
 static inline void hardlockup_detector_disable(void) {}
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 8fbfda94a67b..367aa81294ef 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -44,7 +44,7 @@ int __read_mostly soft_watchdog_user_enabled = 1;
 int __read_mostly watchdog_thresh = 10;
 int __read_mostly nmi_watchdog_available;
 
-struct cpumask watchdog_allowed_mask __read_mostly;
+static struct cpumask watchdog_allowed_mask __read_mostly;
 
 struct cpumask watchdog_cpumask __read_mostly;
 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
@@ -92,6 +92,11 @@ static int __init hardlockup_all_cpu_backtrace_setup(char *str)
 }
 __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
 # endif /* CONFIG_SMP */
+
+struct cpumask *watchdog_get_allowed_cpumask(void)
+{
+	return &watchdog_allowed_mask;
+}
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
 /*
-- 
2.17.1