samples: pktgen: fix proc_cmd command result check logic

Currently, proc_cmd is used to dispatch command to 'pg_ctrl', 'pg_thread',
'pg_set'. proc_cmd is designed to check command result with grep the
"Result:", but this might fail since this string is only shown in
'pg_thread' and 'pg_set'.

This commit fixes this logic by grep-ing the "Result:" string only when
the command is not for 'pg_ctrl'.

For clarity of an execution flow, 'errexit' flag has been set.

To cleanup pktgen on exit, trap has been added for EXIT signal.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/pktgen/functions.sh

@@ -5,6 +5,8 @@
 # Author: Jesper Dangaaard Brouer
 # License: GPL
 
+set -o errexit
+
 ## -- General shell logging cmds --
 function err() {
     local exitcode=$1
@@ -58,6 +60,7 @@ function pg_set() {
 function proc_cmd() {
     local result
     local proc_file=$1
+    local status=0
     # after shift, the remaining args are contained in $@
     shift
     local proc_ctrl=${PROC_DIR}/$proc_file
@@ -73,13 +76,13 @@ function proc_cmd() {
 	echo "cmd: $@ > $proc_ctrl"
     fi
     # Quoting of "$@" is important for space expansion
-    echo "$@" > "$proc_ctrl"
-    local status=$?
+    echo "$@" > "$proc_ctrl" || status=$?
 
-    result=$(grep "Result: OK:" $proc_ctrl)
-    # Due to pgctrl, cannot use exit code $? from grep
-    if [[ "$result" == "" ]]; then
-	grep "Result:" $proc_ctrl >&2
+    if [[ "$proc_file" != "pgctrl" ]]; then
+        result=$(grep "Result: OK:" $proc_ctrl) || true
+        if [[ "$result" == "" ]]; then
+            grep "Result:" $proc_ctrl >&2
+        fi
     fi
     if (( $status != 0 )); then
 	err 5 "Write error($status) occurred cmd: \"$@ > $proc_ctrl\""
@@ -105,6 +108,8 @@ function pgset() {
     fi
 }
 
+[[ $EUID -eq 0 ]] && trap 'pg_ctrl "reset"' EXIT
+
 ## -- General shell tricks --
 
 function root_check_run_with_sudo() {