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notifiers: add tracepoints to the notifiers infrastructure 

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.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20230314200058.1326909-1-gpiccoli@igalia.com
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Guilherme G. Piccoli <kernel@gpiccoli.net>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Guilherme G. Piccoli 2023-03-14 17:00:58 -03:00 committed by Andrew Morton
parent 882c5b261f
commit f4708a82dc
2 changed files with 75 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
include/trace/events/notifier.h Normal file
View File

@ -0,0 +1,69 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM notifier
#if !defined(_TRACE_NOTIFIERS_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_NOTIFIERS_H
#include <linux/tracepoint.h>
DECLARE_EVENT_CLASS(notifier_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)
);
/*
* notifier_register - called upon notifier callback registration
*
* @cb: callback pointer
*
*/
DEFINE_EVENT(notifier_info, notifier_register,
TP_PROTO(void *cb),
TP_ARGS(cb)
);
/*
* notifier_unregister - called upon notifier callback unregistration
*
* @cb: callback pointer
*
*/
DEFINE_EVENT(notifier_info, notifier_unregister,
TP_PROTO(void *cb),
TP_ARGS(cb)
);
/*
* notifier_run - called upon notifier callback execution
*
* @cb: callback pointer
*
*/
DEFINE_EVENT(notifier_info, notifier_run,
TP_PROTO(void *cb),
TP_ARGS(cb)
);
#endif /* _TRACE_NOTIFIERS_H */
/* This part must be outside protection */
#include <trace/define_trace.h>

6
kernel/notifier.c
View File

@ -7,6 +7,9 @@
#include <linux/vmalloc.h>
#include <linux/reboot.h>
#define CREATE_TRACE_POINTS
#include <trace/events/notifier.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(struct notifier_block **nl,
}
n->next = *nl;
rcu_assign_pointer(*nl, n);
trace_notifier_register((void *)n->notifier_call);
return 0;
}
@ -46,6 +50,7 @@ static int notifier_chain_unregister(struct notifier_block **nl,
while ((*nl) != NULL) {
if ((*nl) == n) {
rcu_assign_pointer(*nl, n->next);
trace_notifier_unregister((void *)n->notifier_call);
return 0;
}
nl = &((*nl)->next);
@ -84,6 +89,7 @@ static int notifier_call_chain(struct notifier_block **nl,
continue;
}
#endif
trace_notifier_run((void *)nb->notifier_call);
ret = nb->notifier_call(nb, val, v);
if (nr_calls)