ftracetest: Fix instance test to use proper shell command for pids

The ftracetest instance test used parsing of the "jobs" output to find the
pid of the subshell that is executed previously. But this is not portable to
all major shells that may run these tests. The proper way to get the pid of
the subshell is the shell command "$!". This will return the pid of the
previously executed command. Use that instead, otherwise the test does not
work in all environments.

Link: http://lkml.kernel.org/r/20151211143617.65f4d7a1@gandalf.local.home
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/tools/testing/selftests/ftrace/test.d/instances/instance.tc b/tools/testing/selftests/ftrace/test.d/instances/instance.tc
index 773e276ff90b982a2bf24a44388f76b6ccdf4e9e..1e1abe0ad354267507dc0514351d651e19fd1fb6 100644 (file)
--- a/tools/testing/selftests/ftrace/test.d/instances/instance.tc
+++ b/tools/testing/selftests/ftrace/test.d/instances/instance.tc
@@ -39,28 +39,23 @@ instance_slam() {
 }
 
 instance_slam &
-x=`jobs -l`
-p1=`echo $x | cut -d' ' -f2`
+p1=$!
 echo $p1
 
 instance_slam &
-x=`jobs -l | tail -1`
-p2=`echo $x | cut -d' ' -f2`
+p2=$!
 echo $p2
 
 instance_slam &
-x=`jobs -l | tail -1`
-p3=`echo $x | cut -d' ' -f2`
+p3=$!
 echo $p3
 
 instance_slam &
-x=`jobs -l | tail -1`
-p4=`echo $x | cut -d' ' -f2`
+p4=$!
 echo $p4
 
 instance_slam &
-x=`jobs -l | tail -1`
-p5=`echo $x | cut -d' ' -f2`
+p5=$!
 echo $p5
 
 ls -lR >/dev/null