linux-kernel - [PATCH v7 16/24] watchdog/hardlockup: Define a generic function to detect hardlockups

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Date:   Wed,  1 Mar 2023 15:47:45 -0800
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Len Brown <len.brown@...el.com>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        linuxppc-dev@...ts.ozlabs.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v7 16/24] watchdog/hardlockup: Define a generic function to detect hardlockups

The procedure to detect hardlockups is independent of the source of the
the non-maskable interrupt that drives it. Place it in a separate, generic
function to be invoked by various implementations of the NMI watchdog.

Move the bulk of watchdog_overflow_callback() to the new function
inspect_for_hardlockups(). This function can then be called from the
applicable NMI handlers. No functional changes.

Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Cc: iommu@...ts.linux-foundation.org
Cc: linuxppc-dev@...ts.ozlabs.org
Reviewed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
Changes since v6:
 * None

Changes since v5:
 * None

Changes since v4:
 * None

Changes since v3:
 * None

Changes since v2:
 * None

Changes since v1:
 * None
---
 include/linux/nmi.h   |  1 +
 kernel/watchdog_hld.c | 18 +++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 048c0b9aa623..75038cb2710e 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -209,6 +209,7 @@ int proc_nmi_watchdog(struct ctl_table *, int , void *, size_t *, loff_t *);
 int proc_soft_watchdog(struct ctl_table *, int , void *, size_t *, loff_t *);
 int proc_watchdog_thresh(struct ctl_table *, int , void *, size_t *, loff_t *);
 int proc_watchdog_cpumask(struct ctl_table *, int, void *, size_t *, loff_t *);
+void inspect_for_hardlockups(struct pt_regs *regs);
 
 #ifdef CONFIG_HAVE_ACPI_APEI_NMI
 #include <asm/nmi.h>
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index 247bf0b1582c..b352e507b17f 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -106,14 +106,8 @@ static struct perf_event_attr wd_hw_attr = {
 	.disabled	= 1,
 };
 
-/* Callback function for perf event subsystem */
-static void watchdog_overflow_callback(struct perf_event *event,
-				       struct perf_sample_data *data,
-				       struct pt_regs *regs)
+void inspect_for_hardlockups(struct pt_regs *regs)
 {
-	/* Ensure the watchdog never gets throttled */
-	event->hw.interrupts = 0;
-
 	if (__this_cpu_read(watchdog_nmi_touch) == true) {
 		__this_cpu_write(watchdog_nmi_touch, false);
 		return;
@@ -163,6 +157,16 @@ static void watchdog_overflow_callback(struct perf_event *event,
 	return;
 }
 
+/* Callback function for perf event subsystem */
+static void watchdog_overflow_callback(struct perf_event *event,
+				       struct perf_sample_data *data,
+				       struct pt_regs *regs)
+{
+	/* Ensure the watchdog never gets throttled */
+	event->hw.interrupts = 0;
+	inspect_for_hardlockups(regs);
+}
+
 static int hardlockup_detector_event_create(void)
 {
 	unsigned int cpu = smp_processor_id();
-- 
2.25.1