Right now there is one arch (sparc64) that selects HAVE_NMI_WATCHDOG
without selecting HAVE_HARDLOCKUP_DETECTOR_ARCH. Because of that one
architecture, we have some special case code in the watchdog core to
handle the fact that watchdog_hardlockup_probe() isn't implemented.
Let's implement watchdog_hardlockup_probe() for sparc64 and get rid of
the special case.
As a side effect of doing this, code inspection tells us that we could
fix a minor bug where the system won't properly realize that NMI
watchdogs are disabled. Specifically, on powerpc if
CONFIG_PPC_WATCHDOG is turned off the arch might still select
CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH which selects
CONFIG_HAVE_NMI_WATCHDOG. Since CONFIG_PPC_WATCHDOG was off then
nothing will override the "weak" watchdog_hardlockup_probe() and we'll
fallback to looking at CONFIG_HAVE_NMI_WATCHDOG.
Suggested-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
Though this does fix a minor bug, I didn't mark this as "Fixes"
because it's super minor. One could also argue that this wasn't a bug
at all but simply was never an implemented feature. The code that
added some amount of dynamicness here was commit a994a3147e4c
("watchdog/hardlockup/perf: Implement init time detection of perf")
which, as per the title, was only intending to make "perf"
dynamic. The old NMI watchdog presumably has never been handled
dynamically.
arch/Kconfig | 3 ++-
arch/sparc/kernel/nmi.c | 5 +++++
kernel/watchdog.c | 13 -------------
3 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 64d771855ecd..b4f6387b12fe 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -428,7 +428,8 @@ config HAVE_NMI_WATCHDOG
bool
help
The arch provides a low level NMI watchdog. It provides
- asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
+ asm/nmi.h, and defines its own watchdog_hardlockup_probe() and
+ arch_touch_nmi_watchdog().
config HAVE_HARDLOCKUP_DETECTOR_ARCH
bool
diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index 9d9e29b75c43..17cdfdbf1f3b 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -65,6 +65,11 @@ void arch_touch_nmi_watchdog(void)
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);
+int __init watchdog_hardlockup_probe(void)
+{
+ return 0;
+}
+
static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
{
int this_cpu = smp_processor_id();
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 4b9e31edb47f..62230f5b8878 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -217,19 +217,6 @@ void __weak watchdog_hardlockup_disable(unsigned int cpu) { }
*/
int __weak __init watchdog_hardlockup_probe(void)
{
- /*
- * If CONFIG_HAVE_NMI_WATCHDOG is defined then an architecture
- * is assumed to have the hard watchdog available and we return 0.
- */
- if (IS_ENABLED(CONFIG_HAVE_NMI_WATCHDOG))
- return 0;
-
- /*
- * Hardlockup detectors other than those using CONFIG_HAVE_NMI_WATCHDOG
- * are required to implement a non-weak version of this probe function
- * to tell whether they are available. If they don't override then
- * we'll return -ENODEV.
- */
return -ENODEV;
}
--
2.41.0.rc0.172.g3f132b7071-goog
