linux-kernel - [for-linus][PATCH 6/7] kernel/trace: Fix do not unregister tracepoints when register sched_migrate

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Message-Id: <20200106211958.579504490@goodmis.org>
Date:   Mon, 06 Jan 2020 16:19:07 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable@...r.kernel.org, Kaitao Cheng <pilgrimtao@...il.com>
Subject: [for-linus][PATCH 6/7] kernel/trace: Fix do not unregister tracepoints when register
 sched_migrate_task fail

From: Kaitao Cheng <pilgrimtao@...il.com>

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@...r.kernel.org
Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing")
Signed-off-by: Kaitao Cheng <pilgrimtao@...il.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/trace_sched_wakeup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 5e43b9664eca..617e297f46dc 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -630,7 +630,7 @@ static void start_wakeup_tracer(struct trace_array *tr)
 	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);
@@ -648,6 +648,8 @@ static void start_wakeup_tracer(struct trace_array *tr)
 		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:
-- 
2.24.0