[PATCH] tracing/hwlat: select TRACER_MAX_TRACE

[Arnd Bergmann]

hwlat_trace cannot work without CONFIG_TRACER_MAX_TRACE:

kernel/trace/trace_hwlat.c: In function 'get_sample':
kernel/trace/trace_hwlat.c:258:18: error: 'struct trace_array' has no member named 'max_latency'; did you mean 'max_lock'?
   if (sample > tr->max_latency)
                  ^~
kernel/trace/trace_hwlat.c:259:6: error: 'struct trace_array' has no member named 'max_latency'; did you mean 'max_lock'?
    tr->max_latency = sample;
      ^~
kernel/trace/trace_hwlat.c: In function 'hwlat_tracer_init':
kernel/trace/trace_hwlat.c:583:4: error: 'struct trace_array' has no member named 'max_latency'; did you mean 'max_lock'?
  tr->max_latency = 0;

We also have to enable CONFIG_TRACER_SNAPSHOT, which in turn
is a dependency of CONFIG_TRACER_MAX_TRACE.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: e7c15cd8a113 ("tracing: Added hardware latency tracer")
---
 kernel/trace/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 2a96b063d659..54ef701dbd8a 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -219,6 +219,8 @@ config SCHED_TRACER
 config HWLAT_TRACER
 	bool "Tracer to detect hardware latencies (like SMIs)"
 	select GENERIC_TRACER
+	select TRACER_MAX_TRACE
+	select TRACER_SNAPSHOT
 	help
 	 This tracer, when enabled will create one or more kernel threads,
 	 depening on what the cpumask file is set to, which each thread
-- 
2.9.0