iotest failure -- test possibly not using sufficiently unique temp filename?

[Peter Maydell]

Hi; I just saw this iotest failure (on an s390x box, as it happens):

  TEST    iotest-qcow2: 130 [fail]
QEMU          --
"/home/linux1/qemu/build/all/tests/qemu-iotests/../../s390x-softmmu/qemu-system-s390x"
-nodefaults -display none -machine accel=qtest
QEMU_IMG      -- "/home/linux1/qemu/build/all/tests/qemu-iotests/../../qemu-img"
QEMU_IO       --
"/home/linux1/qemu/build/all/tests/qemu-iotests/../../qemu-io"
--cache writeback -f qcow2
QEMU_NBD      -- "/home/linux1/qemu/build/all/tests/qemu-iotests/../../qemu-nbd"
IMGFMT        -- qcow2 (compat=1.1)
IMGPROTO      -- file
PLATFORM      -- Linux/s390x lxub05 4.15.0-58-generic
TEST_DIR      -- /home/linux1/qemu/build/all/tests/qemu-iotests/scratch
SOCKET_SCM_HELPER --
/home/linux1/qemu/build/all/tests/qemu-iotests/socket_scm_helper

--- /home/linux1/qemu/tests/qemu-iotests/130.out        2019-05-10
12:27:16.948075733 -0400
+++ /home/linux1/qemu/build/all/tests/qemu-iotests/130.out.bad
2019-09-27 12:01:23.649722655 -0400
@@ -18,20 +18,22 @@
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) commit testdisk
 (qemu)
-image: TEST_DIR/t.IMGFMT
-file format: IMGFMT
-virtual size: 64 MiB (67108864 bytes)
-backing file: TEST_DIR/t.IMGFMT.orig
-backing file format: raw
+qemu-img: Could not open 'TEST_DIR/t.IMGFMT': Failed to get shared "write" lock
+Is another process using the image [TEST_DIR/t.IMGFMT]?

 === Marking image dirty (lazy refcounts) ===

+qemu-img: TEST_DIR/t.IMGFMT: Failed to get "write" lock
+Is another process using the image [TEST_DIR/t.IMGFMT]?
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
-wrote 4096/4096 bytes at offset 0
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io: can't open device
/home/linux1/qemu/build/all/tests/qemu-iotests/scratch/t.qcow2: Failed
to get "write" lock
+Is another process using the image
[/home/linux1/qemu/build/all/tests/qemu-iotests/scratch/t.qcow2]?
+no file open, try 'help open'
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
 virtual size: 64 MiB (67108864 bytes)
+backing file: TEST_DIR/t.IMGFMT.orig
+backing file format: raw
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
backing_file=TEST_DIR/t.IMGFMT.orig backing_fmt=raw
 wrote 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)



This looks suspiciously like the test isn't using a unique
filename for its disk image: "qemu-iotests/scratch/t.qcow2"
in the build directory, and so perhaps it has collided with
another iotest ?

If we run 'make check' with a -j<something> option do the
iotests all get run serially anyway, or do they run in
parallel against each other ?

thanks
-- PMM