[RFC PATCH v2 09/14] watchdog/hardlockup: Make arch_touch_nmi_watchdog() to hpet-based implementation

[Ricardo Neri]

CPU architectures that have an NMI watchdog use arch_touch_nmi_watchdog()
to briefly ignore the hardlockup detector. If the architecture does not
have an NMI watchdog, one can be constructed using a source of non-
maskable interrupts. In this case, arch_touch_nmi_watchdog() is common
to any underlying hardware resource used to drive the detector and needs
to be available to other kernel subsystems if hardware different from perf
drives the detector.

There exists perf-based and HPET-based implementations. Make it available
to the latter.

For clarity, wrap this function in a separate preprocessor conditional
from functions which are truly specific to the perf-based implementation.

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: "David S. Miller" <davem at davemloft.net>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
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: 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 | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 5a8b19749769..bf5ebcfdd590 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -94,8 +94,16 @@ static inline void hardlockup_detector_disable(void) {}
 # define NMI_WATCHDOG_SYSCTL_PERM	0444
 #endif
 
-#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF) || \
+    defined(CONFIG_X86_HARDLOCKUP_DETECTOR_HPET)
 extern void arch_touch_nmi_watchdog(void);
+#else
+# if !defined(CONFIG_HAVE_NMI_WATCHDOG)
+static inline void arch_touch_nmi_watchdog(void) {}
+# endif
+#endif
+
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
 extern void hardlockup_detector_perf_stop(void);
 extern void hardlockup_detector_perf_restart(void);
 extern void hardlockup_detector_perf_disable(void);
-- 
2.17.1