[PATCH v2] selftests/ftrace: Limit length in subsystem-enable tests

[Yuanhe Shu]

While sched* events being traced and sched* events continuously happen,
"[xx] event tracing - enable/disable with subsystem level files" would
not stop as on some slower systems it seems to take forever.
Select the first 100 lines of output would be enough to judge whether
there are more than 3 types of sched events.

Fixes: 815b18ea66d6 ("ftracetest: Add basic event tracing test cases")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Yuanhe Shu <xiangzao@xxxxxxxxxxxxxxxxx>
---
 .../selftests/ftrace/test.d/event/subsystem-enable.tc       | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
index b1ede6249866..b7c8f29c09a9 100644
--- a/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
+++ b/tools/testing/selftests/ftrace/test.d/event/subsystem-enable.tc
@@ -18,7 +18,7 @@ echo 'sched:*' > set_event
 
 yield
 
-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
 if [ $count -lt 3 ]; then
     fail "at least fork, exec and exit events should be recorded"
 fi
@@ -29,7 +29,7 @@ echo 1 > events/sched/enable
 
 yield
 
-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
 if [ $count -lt 3 ]; then
     fail "at least fork, exec and exit events should be recorded"
 fi
@@ -40,7 +40,7 @@ echo 0 > events/sched/enable
 
 yield
 
-count=`cat trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
+count=`head -n 100 trace | grep -v ^# | awk '{ print $5 }' | sort -u | wc -l`
 if [ $count -ne 0 ]; then
     fail "any of scheduler events should not be recorded"
 fi
-- 
2.39.3