tracing/hwlat: Honor the tracing_cpumask

commit 96b4833b6827a62c295b149213c68b559514c929 upstream.

In calculation of the cpu mask for the hwlat kernel thread, the wrong
cpu mask is used instead of the tracing_cpumask, this causes the
tracing/tracing_cpumask useless for hwlat tracer. Fixes it.

Link: https://lkml.kernel.org/r/20200730082318.42584-2-haokexin@gmail.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index bff6c033d70e22e901f6a420975ed11e244992f9..64a98a5bb64105b367f3192579995a566def97f5 100644 (file)
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -272,6 +272,7 @@ static bool disable_migrate;
 static void move_to_next_cpu(void)
 {
        struct cpumask *current_mask = &save_cpumask;
+       struct trace_array *tr = hwlat_trace;
        int next_cpu;
 
        if (disable_migrate)
@@ -285,7 +286,7 @@ static void move_to_next_cpu(void)
                goto disable;
 
        get_online_cpus();
-       cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
+       cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
        next_cpu = cpumask_next(smp_processor_id(), current_mask);
        put_online_cpus();
 
@@ -359,7 +360,7 @@ static int start_kthread(struct trace_array *tr)
        /* Just pick the first CPU on first iteration */
        current_mask = &save_cpumask;
        get_online_cpus();
-       cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
+       cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask);
        put_online_cpus();
        next_cpu = cpumask_first(current_mask);