kernel/watchdog.c: move shared definitions to nmi.h

Patch series "Clean up watchdog handlers", v2.

This is an attempt to cleanup watchdog handlers.  Right now,
kernel/watchdog.c implements both softlockup and hardlockup detectors.
Softlockup code is generic.  Hardlockup code is arch specific.  Some
architectures don't use hardlockup detectors.  They use their own
watchdog detectors.  To make both these combination work, we have
numerous #ifdefs in kernel/watchdog.c.

We are trying here to make these handlers independent of each other.
Also provide an interface for architectures to implement their own
handlers.  watchdog_nmi_enable and watchdog_nmi_disable will be defined
as weak such that architectures can override its definitions.

Thanks to Don Zickus for his suggestions.
Here are our previous discussions
http://www.spinics.net/lists/sparclinux/msg16543.html
http://www.spinics.net/lists/sparclinux/msg16441.html

This patch (of 3):

Move shared macros and definitions to nmi.h so that watchdog.c, new file
watchdog_hld.c or any other architecture specific handler can use those
definitions.

Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.com
Signed-off-by: Babu Moger <babu.moger@oracle.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Josh Hunt <johunt@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index a78c35cff1ae..aacca824a6ae 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -7,6 +7,23 @@
 #include <linux/sched.h>
 #include <asm/irq.h>
 
+/*
+ * The run state of the lockup detectors is controlled by the content of the
+ * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit -
+ * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector.
+ *
+ * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled'
+ * are variables that are only used as an 'interface' between the parameters
+ * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The
+ * 'watchdog_thresh' variable is handled differently because its value is not
+ * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh'
+ * is equal zero.
+ */
+#define NMI_WATCHDOG_ENABLED_BIT   0
+#define SOFT_WATCHDOG_ENABLED_BIT  1
+#define NMI_WATCHDOG_ENABLED      (1 << NMI_WATCHDOG_ENABLED_BIT)
+#define SOFT_WATCHDOG_ENABLED     (1 << SOFT_WATCHDOG_ENABLED_BIT)
+
 /**
  * touch_nmi_watchdog - restart NMI watchdog timeout.
  * 
@@ -91,9 +108,16 @@ extern int nmi_watchdog_enabled;
 extern int soft_watchdog_enabled;
 extern int watchdog_user_enabled;
 extern int watchdog_thresh;
+extern unsigned long watchdog_enabled;
 extern unsigned long *watchdog_cpumask_bits;
+#ifdef CONFIG_SMP
 extern int sysctl_softlockup_all_cpu_backtrace;
 extern int sysctl_hardlockup_all_cpu_backtrace;
+#else
+#define sysctl_softlockup_all_cpu_backtrace 0
+#define sysctl_hardlockup_all_cpu_backtrace 0
+#endif
+extern bool is_hardlockup(void);
 struct ctl_table;
 extern int proc_watchdog(struct ctl_table *, int ,
 			 void __user *, size_t *, loff_t *);