perf test vfs_getname: Disable ~/.perfconfig to get default output

Commit-ID:  4fe94ce1c6ba678b5f12b94bb9996eea4fc99e85
Gitweb:     https://git.kernel.org/tip/4fe94ce1c6ba678b5f12b94bb9996eea4fc99e85
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Tue, 30 Jul 2019 11:37:44 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Mon, 12 Aug 2019 16:26:02 -0300

perf test vfs_getname: Disable ~/.perfconfig to get default output

To get the expected output we have to ignore whatever changes the user has in its ~/.perfconfig file, so set PERF_CONFIG to /dev/null to achieve that.

Before:

  # egrep 'trace|show_' ~/.perfconfig
  [trace]
  	show_zeros = yes
  	show_duration = no
  	show_timestamp = no
  	show_arg_names = no
  	show_prefix = yes
  # echo $PERF_CONFIG

  # perf test "trace + vfs_getname"
  70: Check open filename arg using perf trace + vfs_getname: FAILED!
  # export PERF_CONFIG=/dev/null
  # perf test "trace + vfs_getname"
  70: Check open filename arg using perf trace + vfs_getname: Ok
  #

After:

  # egrep 'trace|show_' ~/.perfconfig
  [trace]
  	show_zeros = yes
  	show_duration = no
  	show_timestamp = no
  	show_arg_names = no
  	show_prefix = yes
  # echo $PERF_CONFIG

  # perf test "trace + vfs_getname"
  70: Check open filename arg using perf trace + vfs_getname: Ok
  #

---
 tools/perf/tests/shell/trace+probe_vfs_getname.sh | 4 ++++
 1 file changed, 4 insertions(+)

index 45d269b0157e..11cc2af13f2b 100755
@@ -32,6 +32,10 @@ if [ $err -ne 0 ] ; then
 	exit $err
 fi
 
+# Do not use whatever ~/.perfconfig file, it may change the output
+# via trace.{show_timestamp,show_prefix,etc}
+export PERF_CONFIG=/dev/null
+
 trace_open_vfs_getname
 err=$?
 rm -f ${file}