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

[Ricardo Neri]

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 at zytor.com>
Cc: Ashok Raj <ashok.raj at intel.com>
Cc: Andi Kleen <andi.kleen at intel.com>
Cc: Tony Luck <tony.luck at intel.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki at intel.com>
Cc: Don Zickus <dzickus at redhat.com>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Frederic Weisbecker <frederic at kernel.org>
Cc: Alexei Starovoitov <ast at kernel.org>
Cc: Babu Moger <babu.moger at oracle.com>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
Cc: Masami Hiramatsu <mhiramat at kernel.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Philippe Ombredanne <pombredanne at nexb.com>
Cc: Colin Ian King <colin.king at canonical.com>
Cc: Byungchul Park <byungchul.park at lge.com>
Cc: "Paul E. McKenney" <paulmck at linux.vnet.ibm.com>
Cc: "Luis R. Rodriguez" <mcgrof at kernel.org>
Cc: Waiman Long <longman at redhat.com>
Cc: Josh Poimboeuf <jpoimboe at redhat.com>
Cc: Randy Dunlap <rdunlap at infradead.org>
Cc: Davidlohr Bueso <dave at stgolabs.net>
Cc: Christoffer Dall <cdall at linaro.org>
Cc: Marc Zyngier <marc.zyngier at arm.com>
Cc: Kai-Heng Feng <kai.heng.feng at canonical.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: David Rientjes <rientjes at google.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar at intel.com>
Cc: x86 at kernel.org
Cc: "David S. Miller" <davem at davemloft.net>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: sparclinux at vger.kernel.org
Cc: linuxppc-dev at lists.ozlabs.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon at linux.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