4.19.94-rt39-rc2 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Daniel Wagner <redacted>

[ Upstream commit af3c1c5fdf177870fb5e6e16b24e374696ab28f5 ]

The current->migrate_disable counter is not always defined leading to
build failures with DEBUG_PREEMPT && !PREEMPT_RT_BASE.

Restrict the access to ->migrate_disable to same set where
->migrate_disable is modified.

Signed-off-by: Daniel Wagner <redacted>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bigeasy: adjust condition + description]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 lib/smp_processor_id.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 0c80992aa337..2e7398534b66 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c

@@ -22,8 +22,10 @@ notrace static unsigned int check_preemption_disabled(const char *what1,
 	 * Kernel threads bound to a single CPU can safely use
 	 * smp_processor_id():
 	 */
+#if defined(CONFIG_PREEMPT_RT_BASE) && (defined(CONFIG_SMP) || defined(CONFIG_SCHED_DEBUG))
 	if (current->migrate_disable)
 		goto out;
+#endif
 
 	if (current->nr_cpus_allowed == 1)
 		goto out;

-- 
2.24.1