The patch titled
Subject: notifiers: add tracepoints to the notifiers infrastructure
has been added to the -mm mm-nonmm-unstable branch. Its filename is
notifiers-add-tracepoints-to-the-notifiers-infrastructure.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/notifiers-add-tracepoints-to-the-notifiers-infrastructure.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>
Subject: notifiers: add tracepoints to the notifiers infrastructure
Date: Tue, 14 Mar 2023 17:00:58 -0300
Currently there is no way to show the callback names for registered,
unregistered or executed notifiers. This is very useful for debug
purposes, hence add this functionality here in the form of notifiers'
tracepoints, one per operation.
Link: https://lkml.kernel.org/r/20230314200058.1326909-1-gpiccoli@xxxxxxxxxx
Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Cc: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
Cc: Guilherme G. Piccoli <kernel@xxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- /dev/null
+++ a/include/trace/events/notifiers.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM notifiers
+
+#if !defined(_TRACE_NOTIFIERS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NOTIFIERS_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(notifiers_info,
+
+ TP_PROTO(void *cb),
+
+ TP_ARGS(cb),
+
+ TP_STRUCT__entry(
+ __field(void *, cb)
+ ),
+
+ TP_fast_assign(
+ __entry->cb = cb;
+ ),
+
+ TP_printk("%ps", __entry->cb)
+);
+
+/*
+ * notifiers_register - called upon notifier callback registration
+ *
+ * @cb: callback pointer
+ *
+ */
+DEFINE_EVENT(notifiers_info, notifiers_register,
+
+ TP_PROTO(void *cb),
+
+ TP_ARGS(cb)
+);
+
+/*
+ * notifiers_unregister - called upon notifier callback unregistration
+ *
+ * @cb: callback pointer
+ *
+ */
+DEFINE_EVENT(notifiers_info, notifiers_unregister,
+
+ TP_PROTO(void *cb),
+
+ TP_ARGS(cb)
+);
+
+/*
+ * notifiers_run - called upon notifier callback execution
+ *
+ * @cb: callback pointer
+ *
+ */
+DEFINE_EVENT(notifiers_info, notifiers_run,
+
+ TP_PROTO(void *cb),
+
+ TP_ARGS(cb)
+);
+
+#endif /* _TRACE_NOTIFIERS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--- a/kernel/notifier.c~notifiers-add-tracepoints-to-the-notifiers-infrastructure
+++ a/kernel/notifier.c
@@ -7,6 +7,9 @@
#include <linux/vmalloc.h>
#include <linux/reboot.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/notifiers.h>
+
/*
* Notifier list for kernel code which wants to be called
* at shutdown. This is used to stop any idling DMA operations
@@ -37,6 +40,7 @@ static int notifier_chain_register(struc
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
+ trace_notifiers_register((void*)n->notifier_call);
return 0;
}
@@ -46,6 +50,7 @@ static int notifier_chain_unregister(str
while ((*nl) != NULL) {
if ((*nl) == n) {
rcu_assign_pointer(*nl, n->next);
+ trace_notifiers_unregister((void*)n->notifier_call);
return 0;
}
nl = &((*nl)->next);
@@ -84,6 +89,7 @@ static int notifier_call_chain(struct no
continue;
}
#endif
+ trace_notifiers_run((void*)nb->notifier_call);
ret = nb->notifier_call(nb, val, v);
if (nr_calls)
_
Patches currently in -mm which might be from gpiccoli@xxxxxxxxxx are
notifiers-add-tracepoints-to-the-notifiers-infrastructure.patch
