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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kaitao Cheng <pilgrimtao@gmail.com>,
        "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Subject: [PATCH 4.4 05/28] kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail
Date:   Tue, 14 Jan 2020 11:02:07 +0100
Message-Id: <20200114094340.513473929@linuxfoundation.org>
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From: Kaitao Cheng <pilgrimtao@gmail.com>

commit 50f9ad607ea891a9308e67b81f774c71736d1098 upstream.

In the function, if register_trace_sched_migrate_task() returns error,
sched_switch/sched_wakeup_new/sched_wakeup won't unregister. That is
why fail_deprobe_sched_switch was added.

Link: http://lkml.kernel.org/r/20191231133530.2794-1-pilgrimtao@gmail.com

Cc: stable@vger.kernel.org
Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing")
Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/trace/trace_sched_wakeup.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -625,7 +625,7 @@ static void start_wakeup_tracer(struct t
 	if (ret) {
 		pr_info("wakeup trace: Couldn't activate tracepoint"
 			" probe to kernel_sched_migrate_task\n");
-		return;
+		goto fail_deprobe_sched_switch;
 	}
 
 	wakeup_reset(tr);
@@ -643,6 +643,8 @@ static void start_wakeup_tracer(struct t
 		printk(KERN_ERR "failed to start wakeup tracer\n");
 
 	return;
+fail_deprobe_sched_switch:
+	unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
 fail_deprobe_wake_new:
 	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
 fail_deprobe: