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From: wenyang.linux@foxmail.com
To: Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Ingo Molnar <mingo@kernel.org>
Cc: Wen Yang <wenyang.linux@foxmail.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] coredump debugging: add a tracepoint to report the coredumping
Date: Sat, 17 Feb 2024 02:59:47 +0800
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From: Wen Yang <wenyang.linux@foxmail.com>

Currently coredump_task_exit() takes some time to wait for the generation
of the dump file. But if the user-space wants to receive a notification
as soon as possible it maybe inconvenient.

Add the new trace_sched_process_coredump() into coredump_task_exit(),
this way a user-space monitor could easily wait for the exits and
potentially make some preparations in advance.

Signed-off-by: Wen Yang <wenyang.linux@foxmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
---
 include/trace/events/sched.h | 7 +++++++
 kernel/exit.c                | 1 +
 2 files changed, 8 insertions(+)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index dbb01b4b7451..ce7448065986 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -334,6 +334,13 @@ DEFINE_EVENT(sched_process_template, sched_process_exit,
 	     TP_PROTO(struct task_struct *p),
 	     TP_ARGS(p));
 
+/*
+ * Tracepoint for a task coredumping:
+ */
+DEFINE_EVENT(sched_process_template, sched_process_coredump,
+	     TP_PROTO(struct task_struct *p),
+	     TP_ARGS(p));
+
 /*
  * Tracepoint for waiting on task to unschedule:
  */
diff --git a/kernel/exit.c b/kernel/exit.c
index 493647fd7c07..c11e12d73f4e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -425,6 +425,7 @@ static void coredump_task_exit(struct task_struct *tsk)
 			self.next = xchg(&core_state->dumper.next, &self);
 		else
 			self.task = NULL;
+		trace_sched_process_coredump(tsk);
 		/*
 		 * Implies mb(), the result of xchg() must be visible
 		 * to core_state->dumper.
-- 
2.25.1