[PATCH v6 02/10] tracing/osnoise: start_kthread: Always check OSN_WORKLOAD

[Crystal Wood <crwood@redhat.com>]

We can get here on timerlat with OSN_WORKLOAD cleared via
osnoise_hotplug_workfn().

While we're moving this code, remove the pointless compiler barrier
immediately before returning from a function.  Even if it's inlined,
it's not doing anything useful.

Signed-off-by: Crystal Wood <crwood@redhat.com>
---
v6: revive patch
---
 kernel/trace/trace_osnoise.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 953936bd5eec..a6f7fbb342b6 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2046,16 +2046,17 @@ static int start_kthread(unsigned int cpu)
 	if (cpu_osn_var(cpu)->kthread)
 		return 0;
 
+	/* Can still happen with timerlat via cpu hotplug */
+	if (!test_bit(OSN_WORKLOAD, &osnoise_options)) {
+		if (!timerlat_enabled())
+			osn->sampling = true;
+		return 0;
+	}
+
 	if (timerlat_enabled()) {
 		snprintf(comm, 24, "timerlat/%d", cpu);
 		main = timerlat_main;
 	} else {
-		/* if no workload, just return */
-		if (!test_bit(OSN_WORKLOAD, &osnoise_options)) {
-			cpu_osn_var(cpu)->sampling = true;
-			barrier();
-			return 0;
-		}
 		snprintf(comm, 24, "osnoise/%d", cpu);
 	}
 
-- 
2.54.0