[Qemu-devel] [PATCH] qemu-iotests: fix cleanup of background processes

[Jeff Cody <jcody@redhat.com>]

Commit 934659c switched the iotests to run qemu and qemu-nbd from a bash
subshell, in order to catch segfaults.  Unfortunately, this means the
process PID cannot be captured via '$!'. We stopped killing qemu and
qemu-nbd processes, leaving a lot of orphaned, running qemu processes
after executing iotests.

Since the process is using exec in the subshell, the PID is the
same as the subshell PID.

Track these PIDs for cleanup using pidfiles in the $TEST_DIR. Only
track the qemu PID, however, if requested - not all usage requires
killing the process.

Reported-by: John Snow <jsnow@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 tests/qemu-iotests/common.config | 14 ++++++++++++--
 tests/qemu-iotests/common.qemu   | 17 +++++++++++------
 tests/qemu-iotests/common.rc     |  6 +++---
 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/tests/qemu-iotests/common.config b/tests/qemu-iotests/common.config
index 596bb2b..5fd4ca8 100644
--- a/tests/qemu-iotests/common.config
+++ b/tests/qemu-iotests/common.config
@@ -44,6 +44,8 @@ export HOST_OPTIONS=${HOST_OPTIONS:=local.config}
 export CHECK_OPTIONS=${CHECK_OPTIONS:="-g auto"}
 export PWD=`pwd`
 
+export _QEMU_HANDLE=0
+
 # $1 = prog to look for, $2* = default pathnames if not found in $PATH
 set_prog_path()
 {
@@ -105,7 +107,12 @@ fi
 
 _qemu_wrapper()
 {
-    (exec "$QEMU_PROG" $QEMU_OPTIONS "$@")
+    (
+        if [ ! -z ${QEMU_NEED_PID} ]; then
+            echo -n $BASHPID > "${TEST_DIR}/qemu-${_QEMU_HANDLE}.pid"
+        fi
+        exec "$QEMU_PROG" $QEMU_OPTIONS "$@"
+    )
 }
 
 _qemu_img_wrapper()
@@ -120,7 +127,10 @@ _qemu_io_wrapper()
 
 _qemu_nbd_wrapper()
 {
-    (exec "$QEMU_NBD_PROG" $QEMU_NBD_OPTIONS "$@")
+    (
+        echo -n $BASHPID > "${TEST_DIR}/qemu-nbd.pid"
+        exec "$QEMU_NBD_PROG" $QEMU_NBD_OPTIONS "$@"
+    )
 }
 
 export QEMU=_qemu_wrapper
diff --git a/tests/qemu-iotests/common.qemu b/tests/qemu-iotests/common.qemu
index e3faa53..bb108bd 100644
--- a/tests/qemu-iotests/common.qemu
+++ b/tests/qemu-iotests/common.qemu
@@ -30,8 +30,6 @@ QEMU_COMM_TIMEOUT=10
 QEMU_FIFO_IN="${TEST_DIR}/qmp-in-$$"
 QEMU_FIFO_OUT="${TEST_DIR}/qmp-out-$$"
 
-QEMU_PID=
-_QEMU_HANDLE=0
 QEMU_HANDLE=0
 
 # If bash version is >= 4.1, these will be overwritten and dynamic
@@ -153,11 +151,11 @@ function _launch_qemu()
     mkfifo "${fifo_out}"
     mkfifo "${fifo_in}"
 
+    QEMU_NEED_PID='y'\
     ${QEMU} -nographic -serial none ${comm} -machine accel=qtest "${@}" \
                                                                 >"${fifo_out}" \
                                                                 2>&1 \
                                                                 <"${fifo_in}" &
-    QEMU_PID[${_QEMU_HANDLE}]=$!
 
     if [[ "${BASH_VERSINFO[0]}" -ge "5" ||
         ("${BASH_VERSINFO[0]}" -ge "4"  &&  "${BASH_VERSINFO[1]}" -ge "1") ]]
@@ -196,10 +194,17 @@ function _cleanup_qemu()
     # QEMU_PID[], QEMU_IN[], QEMU_OUT[] all use same indices
     for i in "${!QEMU_OUT[@]}"
     do
-        if [ -z "${wait}" ]; then
-            kill -KILL ${QEMU_PID[$i]} 2>/dev/null
+        local QEMU_PID
+        if [ -f "${TEST_DIR}/qemu-${i}.pid" ]; then
+            QEMU_PID=`cat "${TEST_DIR}/qemu-${i}.pid"`
+            rm -f "${TEST_DIR}/qemu-${i}.pid"
+        fi
+        if [ -z "${wait}" ] && [ ! -z ${QEMU_PID} ]; then
+            kill -KILL ${QEMU_PID} 2>/dev/null
+        fi
+        if [ ! -z ${QEMU_PID} ]; then
+            wait ${QEMU_PID} 2>/dev/null # silent kill
         fi
-        wait ${QEMU_PID[$i]} 2>/dev/null # silent kill
         if [ -n "${wait}" ]; then
             cat <&${QEMU_OUT[$i]} | _filter_testdir | _filter_qemu \
                                   | _filter_qemu_io | _filter_qmp
diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index 28e4bea..84d2e98 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -154,7 +154,6 @@ _make_test_img()
     # Start an NBD server on the image file, which is what we'll be talking to
     if [ $IMGPROTO = "nbd" ]; then
         eval "$QEMU_NBD -v -t -b 127.0.0.1 -p 10810 -f $IMGFMT  $TEST_IMG_FILE &"
-        QEMU_NBD_PID=$!
         sleep 1 # FIXME: qemu-nbd needs to be listening before we continue
     fi
 }
@@ -175,8 +174,9 @@ _cleanup_test_img()
     case "$IMGPROTO" in
 
         nbd)
-            if [ -n "$QEMU_NBD_PID" ]; then
-                kill $QEMU_NBD_PID
+            if [ -f "${TEST_DIR}/qemu-nbd.pid" ]; then
+                kill `cat "${TEST_DIR}/qemu-nbd.pid"`
+                rm -f "${TEST_DIR}/qemu-nbd.pid"
             fi
             rm -f "$TEST_IMG_FILE"
             ;;
-- 
1.9.3